Understanding buses... (Bangkok)

OK..now I live (albeit on the wrong visa) in Bangkok, it's become apparent I am not going to be able to get about solely on the BTS and the MRT. The temples/museums area is a bloody long hike for starters. So, does anyone know how the buses work? I managed to get one back into town but the bus stops have a list of numbers on them. No idea what direction I was heading in, no idea of zone or how to pay. This makes even Turkey modern by comparison. I know what you're thinking - why not get a Taxi/Tuk Tuk - well because I trust neither is the short answer.