I have to go now but I can answer the weather question real quick and either me or my new friend Dinosaur Viejo will be happy to answer the other two Im sure.
The weather is hot and humid. Extremely humid and tropical. Thai people like to say they have 3 seasons... hot, hotter, and hottest, and they arent kidding. I was talking to a Thai guy on the plane and he told me "I better take my sweatshirt off", as I was unprepared for the crazy heat even though I arrived in the middle of the night.
Shorts and a T-shirt will do you well enough at anytime of the year here.