Sean John is the clothing line by Sean Comes aka Diddy Kanye IS releasing his own line soon though
Traders in Bangkok are familiar with the Australian clothing sizes and usually have their clothing in cms. Be careful however that usually if only classed as XS S M L etc go for a size up from your usual as these clothe sizes are generally fashioned ...
The malls have stores where you can get all of that. WalMart is a great place too.