Some are air conditioned, some are not. 50 B will take you pretty much anywhere in the downtown area. Tuk-tuks are a tradition in Thailand. Ex-kamikazes drive them. They are generally cheaper than taxis, but they are open-air vehicles that spew clouds of blue exhaust.
Busses are fairly easy to figure out.
There are bus maps at all the stops. For the long-tail boats, dicker for the price. Thai restaurants in the US just don't seem the same to me anymore. All the travel books warn about the food and drink in Thailand, and rightfully so. The books warn against eating from any street vendor.