Sunny Beach is the largest beach resort in Bulgaria. It has more than 800 hotels with more than 300,000 beds.
Everything in Sunny Beach is centered around tourism. It feels more like a fairground than a city. It has little to do with the real Bulgaria. You might as well be in Salou or any other party town.
Mainly via Burgas airport.
There are several places across the resort where you can rent some sort of personal transportation - bikes, rickshaws, segways, motopeds and other.
On foot: distances are not so big, and the most interesting streets are pedestrians-only, so travelling by foot is the preferred transportation for not so long distances.
Tourist 'train': reaches only part of the boulevard. No regular timetable, runs when it's full. Can be a bit of a wait. There are multiple routes, so make sure if the train you see is the train you need. Ticket fee is 3 BGN in one direction (as of August 2012)
By car: not very useful in Sunny Beach. Distances are small, the main streets are pedestrian only and traffic in Bulgaria is rather dangerous.
By horse carriage: not very fast but you travel in style :)
By taxi: Regular fee is 3 BGN/km (as of August 2012). However there might be some scammers, so check the tariff before you enter the cab and keep an eye on the counter.
By bus: There are number of buses between Sunny beach and nearby settlements. You can check map and bus numbers here. Have in mind that during the rush hours the buses can get pretty overcrowded. Ticket fee is 1 BGN (as of August 2012).
By boat: There is boat tour between Sunny beach and Nessebar. The boat docks at the central pier and travels every 20 minutes.
There are various restaurants and kiosks selling food all over the settlement. They are offering different kinds of cuisines - Bulgarian, English, Deutsch... There are small number of Chinese restaurants.
You should not have problem with getting a place to sleep. Literally almost every building you see there is a hotel. However, have in mind that in the summer season most of the places are already taken, so it would be better to not go without a reservation.
As all seaside resorts - be aware for thieves. Keep an eye for your belongings (especially when you are on the beach).
The other main problem you may encounter are drunk people. Don't argue with people that seem affected by alcohol - some of them might become violent.
There are some rumours of food poisoning. Don't eat food that doesn't look good. There are duners and kebaps sold at the streets that might give you a belly ache.
Tap water is safe to drink as well as at most of the places in Bulgaria.
Most of the hotels have wifi zones. Some of them are open, other are paid hotspots.
There are lots of paid phones along the resort streets.
Nessebar is only a few kilometers away.
Irakly is a wild beach nearby. It is popular among campers as it is a true opposite of the Las-Vegas-looking Sunny Beach.
There is a bus station in Sunny Beach. There are regular bus routes to Burgas and Varna (buses to Burgas leaving every 20 minutes). There are also buses to other cities in Bulgaria - Sofia, Plovdiv, Stara Zagora, Vidin, etc...
Burgas and Varna are major transport hubs and once you get there, you can go everywhere.