I lived here for 12 years and worked as a real estate agent. Never ever have any client had to show what visa they hold or had to have a Thai bank account. You only pay the full years rent if you looking for a lower monthly rent price, standard is 1 months rent + 2 months deposit. Anything else is someone trying to take you for a ride. You do need to provide a copy of the ID page of your passport though.
that’s the easiest way. But you can do it yourself too but might be denied in the 40-50 first branches you walk into, and will probably have to buy their insurance for 5k baht which is what an agent charges you. So agent is easier choice.