The ones that offer CELTA or TrinityTESOL. I did a CELTA at ECC Phuket. It's the highest level TEFL you can get. Bit pricey but there is a reason for that. Or just get some ordinary TEFL course but not as good. Anyway strictly you only need degree to get job teaching English
I think he means will it f*** up the account if you just carry on using it as a normal bank account....answer no as long as you have the stipulated funds in there >800k >400k etc at all times. I actually haven't used the account since I put the 800k in it!