you tourist visa is valid to enter Thailand upto 90 days from issue date, when you land you will be stamped into the country for 60 days, if you want to stay longer you can get 1 x 30 days extension at a cost of 1900thb, just go to your local immigration when you have no more than 30 days remaining…..the Coe is valid for your flight and departure date only
if you are here on visa exemption and staying in a hotel you will struggle to open a bank account yourself
What I’m saying is if you choose to use an agent to assist you it is cheaper in Pattaya and the cost will be 3000b and your new account will be at Bangkok bank