OK,
since no one mentioned this essential site, lot of good info on
Thai Visa
In regards of bringing ca$h to Thailand to have some once out of the airport. Sadly my Credit Union has a record of blocking my ATM even when I tell them where I'll be. They did this to me in both Thailand and Hong Kong, and since I normally travel on weekends, it takes over 24 hours before I can talk to anyone back in Texas (no 24 / 7 support).
So I always carry at least $100, and even though the exchange rate is about a cent or two worse at the airport I exchange about that much (well used to, these days I have almost that much Baht with me as I visit Thailand every year).
And even this exchange is pretty much guaranteed to be better than anything in US / Canada (no exchange fees, even if only changing $20, which I've done).