Company account doesn't work for the 500k requirement. You have to have 500k thb or more in a personal account not company. You can then show the deposits to that personal account from the company account.
You'll need 800k thb for the first year regardless. If you make international transfers monthly above the minimum requirements you can switch on year 2, however make sure you transfer more then enough to account for currency conversion shifts.
Depends what province you're in. If it's chiang mai go to the immigration office next to the airport. They have a drive thru and walk up window left side of building just for 90 day reports.
Why did you get In the regular que and not just use a immigration office with a drive thru or 90 day report window? Took me all of 3 minutes to do it myself.
Technically you should update your tm30 everytime you re-enter. If it's just the 90 day report and your old tm 30 address is still the same and covers the current dates(as in you had a 1 or 2 year lease and they put the tm30 term for the entire time) you can use it for your 90 day report, but if you need a residency document or something more official the tm30 will need to match your current visa stamp.