you're talking 100k baht not USD right? No issues with bangkok bank, I transfer 70% of my salary each month in only 1-2 transactions. max it takes is 2 business days but usually same day on weekdays
No matter what visa you have, you are gonna have to pay duty on musical instruments. We brought over a container of household goods with my non-b and the guitars were the only thing we had to pay duty for.