Looks like you win the beer BobMac!! Very good advice too.
The only two things I'd add are............ despite the fact that you're going in June muze, the weather may still be hotter/more humid than you're used to so for daytime wear, I'd ditch the idea of long sleeved shirts and bring short-sleeves instead (forget anything with polyester or similar.....make sure they're natural fibre... cotton is best in the humidity) A light-weight cotton sweater or long sleeved tshirt would be very handy for wearing at night.
Also bring shorts.... you can wear them almost anywhere except temples, high end restaurants or restaurants in hotels. For most other places, shorts and a shirt will be just fine (iin fact, maybe overdressed as so many men wear shorts and polo shirts or tshirts).
You can buy these items at small shops, department stores or market stalls on the street.

And if you hate the insect repellent, you can buy little 'anti-mosquito strips' which are plastic bands like a watchband (adjustable) and impregnated with something like citronella which mozzies don't like. You can wear these around your arms or ankles - not terribly stylish but maybe a better option than repellent. I'm not sure where I bought these, but maybe Watsons (pharmacy chain.... they're all over the place).