Hitchhiking in Bulgaria is very easy and well spread. People do know the concept and also practice it a lot (especially when they are young but not necessarily). Police normally never bother foreigners and even on the motorway (there is only one..) people thumb on the side lane without any problem.
- Bus: Eurolines
Hospitality exchange programs count a huge number of members here, locals as foreigners based all the year long or just some months (rents are really cheap!).
Bulgaria seems to be incredibly difficult to dive due to the sheer amount of competition coming from the homeless and gypsies. Tourist resorts, as ever, may provide things but it would appear to be hit and miss. Sources seem to show that even bakeries take away everything.
Bulgaria is probably the first wireless connected country in Europe, with the highest speed connection also probably. It is quite funny seeing old soviet style trolleybus with always wifi inside..Nearly every park and public areas in the main cities (like Sofia) has a free connection, fact that creates you also big problems if you don't have your own device (people may be surprised and say "everyone has one"..) since there are almost no internet cafes..in Sofia there are only 2, both 3 times more expensive than anywhere else in europe..(some 3-4€/h..maybe just Venice is more..)
Bulgaria is a small and beautiful country in Easter Europe. Crossroads for many vagabonds, travelers and hitchhikers on their way to Turkey, Asia and back it is probably the "poorest" (lowest GDP) country in the EU, and one of the richest for heritage, beauty and culture. Prices are generally cheap (except along the resorts of the Black Sea coast..)compared to the rest of Europe often the half. Most of youngsters speak an excellent English, especially in big cities like Sofia or Plovdiv, the Bulgarian language is Slavic and very similar to Russian (at least for the vocabulary not really the grammar, though don't ever tell it to a Bulgarian..they'll tell you has nothing to do with..) and sometimes also to Serbian; speaking any of them may help you a lot to get around. It offers great opportunities for hitchhiking, work exchange programs and busking.
Take also a look on Alternative Bulgaria's CS group: https://www.couchsurfing.com/groups/alternative-bulgaria