I don't use that immigration office but my one definitely do check. This year I started doing 90 day reports online and have had 2 visits 6 months apart
Normal bank statements from your bank should be used, if they are not in English or Thai you may need to get them officially translated. You don't say where you are applying but different embassies have differing requirements as to how long the 500k must be in your account, some only require it on the most recent statement, some require it on the date of application, some require it to be in the account for 3 months or more
at the end of the day he needs to work out his priorities. Meeting up with mates and risking his visa being rejected, or staying put and wait for the visa
you can only get a 90 day Non-O visa now. Once you are inside Thailand and have money in a Thai bank for 2 months you can apply for a 12 month extension of stay and get a multiple re-entry permit so you can come and go as much as you wish during that time