Citizens of western countries and many others can say for up to 90 days in any 180 day period visa-free. Making a short notice visit to Moldova a distinct possibility. 
Transnistria is not covered by Moldovan visa arrangements but is also fairly straightforward. For most visitors you simply show up at a border entry point, show passport and are admitted.

If an overnight stay in Transnistria is happening then a proof of a hotel booking is asked for, and then you enter. An entry/exit slip of paper is given and this must be retained and produced on exit from the PMR territory. 
 

No, independent travel is possible and is mainly a matter of logistics. Chisinau is easy enough to get to, hotels easy to book online, and public transport is well-developed. To explore more widely and include non-Tiraspol parts of the PMR on a tour is a good idea as it involves expert accompaniment to add more context and information as well as taking care of all the logistics. 

Certain textures of the country as well as some of the ongoing complexities in recent history can be examined in more detail with the help of knowledgeable organisers and local partners. Wine history, tensions that led to the creation of the PMR, the Gagauzian question, and so on are deeper and more nuanced than most expect and accompaniment and curation of such a trip helps to look into these fascinating questions
 

Spring and Autumn. Winer is cold and snowy, summer is hot, but year-round it is accessible so the ‘best’ time is simply a bit more preferable than other times. 
Grapes are harvested in Autumn, and this event takes place nationwide.

Vineyards are at their most spectacular, wine cellars at full productivity, and this key industry can be seen in all its glory at this time. 

National holidays are a good target also, with two days in particular in Transnistria being notable. May 9th is Victory Day (in Moldova too) he anniversary of the defeat of Germany in WWII, so speeches, soviet-style glorification of the sacrifices made in pursuit of the victory, and the march of the Immoral Battalion (descendants of Red Army soldiers) take place everywhere. September 2nd sees the Day of National Autonomy in the PMR, usually marked by miliary parades in central Tiraspol. 
 

Yes, both are generally safe places for all visitors. Apply the usual precautions as there are taxi rip-offs, the occasional tourist scam, opportunism and pickpocketing, but these are not endemic issues, just things to be as aware of as you would anywhere. 

The unique nature of Transnistria often leads to an assumption that it must be riskier; the somewhat oligarchical nature of he place (one company, Sherriff, seems to run everything), the political structure, the presence of a large Russian miliary force, the soviet-vibe, etc. give rise to ideas that it must be a bit dodgy in some il-defined way, but actually it is calm, people are hospitable, and visitors are not so rare enough to be a target or particularly unusual. 

It is worth noting that the proximity of Moldova to Ukraine has added another layer of anxiety for some visitors since 2022, but, while he border is close and war not far away in geographical terms Moldova has not been subject o any miliary action and the situation has remained stable. Responsible companies of course monitor what is going on and will advise guests honestly and soberly about any changes in the situation
 

This is a question with some political and historical baggage that is both fascinating, and somewhat tragic too, but very much worth understanding before a visit. The official language is Moldovan, now called simply ‘Romanian’ by the government. ‘Moldovan’ as a distinct language from Romanian was largely a Russian Imperial and soviet claim to show a difference between Moldova and its neighbour to the west. Romanian is taught in schools, used in government, and is written with the Lain script.

Russian is widely spoken, still to the point of being the main daily language in the country. Anyone who went through education in the USSR or in the first decade or so of independence will have been taught in his language and it therefore crosses generations in a way that Romanian doesn’t. Also, the non-Moldovan population generally speak Russian, so it crosses ethnic lines as well as generations. 

In Gaguazia a Turkic language is spoken, written in Cyrillic usually. Nobody here only speaks Gaguaz though.

In Transnistria, Russian is the language of daily life and all business. There is also ‘Moldovan’ which is basically Romanian written in Cyrillic (Russian is of course written in Cyrillic). 
English is increasingly spoken by young people across all the territories and of course those who have studied it earlier.

In general, Russian is daily language, Romanian growing in relevance, and English good enough to find your way. 
 

No. they are relaxed about what people wear and the sartorial vibe could be described as generically European. 

When visiting churches and monasteries, and there are some sunning ones, the usual expectations apply such as women covering heads and shoulders with a scarf, men and women both avoiding shorts. Scarves are available at the entrances to most such places for visitors to borrow. 
 

None in particular, although in rural and forest areas there are cases of tick-borne encephalitis. Basic precautions, and the usual vaccinations should all be considered in advance. Bottled water is cheap and universal, even when the tap water is safe to drink it is advisable to opt for the bottled stuff. 

Medical facilities are adequate in Moldova, somewhat more basic in most of Transnistria. Both have pharmacies easy to locate and stocked with all the usual medicines. Medical insurance is advisable for any overseas trip. 

Wine is the major industry of Moldova, and probably the cause of most episodes of visitor unwellness too. Needless to say but alcohol should be consumed responsibly, in moderation, and not before or while operating any machinery or controlling any vehicles.

The cure for most wine-related periods of feeling unwell is rest and water. 
 

In Moldova it is developed and advanced. A local sim card or an e-sim can be used, coverage extends in almost all of the country, Wi-Fi is common in cafes, hotels, and so on. The internet is not restricted in any unusual way, so it is like most people will be experienced with.

Transnistria is not the same.

The PMR has it’s own telecoms infrastructure and technically Moldovan sim cards do not work there, although in reality coverage extends in some areas so it is worth keeping an e-sim connected to the Moldovan network valid while there. Wi-Fi is common, in hotels, cafes, etc.

The internet is not all that restricted, so when online you can access almost all you need in the PMR. A common assumption is that it must be like visiting Russia, but it is far more liberal than that in terms of internet accessibility when online, use of foreign social media, and even entertainment options like Neflix and so on. 
 

First, include the two main cities of Chisinau and Tiraspol. For the juxtaposition and because they each have great value to show visitors. Museums, monuments, really interesting architecture from 19th century palaces to soviet-era brutalism and socialist modernism, nightlife, shopping and people-watching. Both cities are distinct but equally viable. 

Wine

Get a to a winery, one of the big ones to experience the scale of the industry. 

Religion

Moldova has remarkable churches and monasteries. Boh the architecture and the history of these are worth seeing and learning about.

Gaguazia

Well worth a visit to see a highly unexpected community of Turkish-speaking, Orthodox Christians, of a disputed and mysterious origin. The Gaguaz also hold a disproportionate influence over the future of Moldova due to autonomy conditions that allow them to seek independence if union with Romania were to take place, so they are historically fascinating, culturally distinct, and politically relevant. 

PMR ex-Tiraspol and Bender.

While the Transnistria capital and its nearby border city are fascinating (the Bender Fortress in an unmissable delight) it is worth seeing more. PMR is small but not micro-state tiny; there are rural areas, industrial settlements, villages and scenic spots, and a taste of the non-urban PMR makes the whole place even more remarkable. 
 

Chisinau International Airport is modern and well equipped and located. Flights from various European cities (as well as some further afield) exist and connections are good through major hubs also. Various airline options exist although capacity on some roues may be limited. 

Overland from Romania is very simple, with numerous border points. Cross by road or take a train to Chisinau from Bucharest or Iasi in Romania. Entry by land from Ukraine was common pre-2022 but is currently not as viable. This situation remains in flux and hopefully will settle positively soon. 

Transnistria has no commercial airport and almost all entry is thus by land from Moldova. The train from Chisinau to Tiraspol is suspended so it is all done by road, across a handful of border points, and with a short stop and passport check being about all that is needed.