Hi Crash,
It's sad about those gibbons, they are so cute and should not be treated the way they do. I don't remember a lot of how the animals were treated when I was last there, but being a SE-asian country, you will see the usual chickens in cages everywhere, and I do mean everywhere. Unfortunatley you will most likely see a lot of animals not doing very well there.
The best way to not cause an international incident there at the moment would be to not smuggle drugs into the counrtry!

lots of problems (particularly with a few certain dumbass Australians who have done so) in that regard. Be sure to get your cases wrapped in plastic at your airport and if it gets opened then report it to customs as soon as you get your bags.
The best advice I can give you is to avoid Phuket completley.. unless you don't mind being ripped off by every single person you encounter there. Bangkok is okay.. I only spent two days there and I had mixed feelings of it. Good night life but very bad food, very dirty and like in Phuket, the locals are very rude/scheming to westerners.
If you do end up going there, you absolutley must go to Phi Phil islands, it was one of the most beautiful places I've ever been to. Also Chiang Mai was great as well, city was nicer and the national parks were fantastic, very pristine jungle wilderness out there I was quite surprised.
I'm afraid I can't really help you out in terms of the way they treat their animals there. I highly doubt it is well, in Phuket you could buy live chickens that they decapitate and wrap in newspaper and sell to people like that, blood oozing through the paper... that was one of the more gross things that I saw there.