If so? then you can't work on that visa. Also it's not a 1 year non0 based on over 50, it would be a 12 month extension, I'm pretty sure you need a non b visa and work permit to work in Thailand.
I believe you have to do the extension in the province you live in, if you move to to a new Provence then you need to do a new tm30 at the new office, As for the 90 day not sure but someone will