Michael,
I'm not sure on the first question. It would probably be best to call the permitting office and find out what the regs are. I think there are certain requirements based on dollar amount and others based on tasks, but I'm not positive. I've avoided getting permits thus far.
To answer the second question, typically, permitted modifications like a garage conversion will show up in the tax records. I'm not sure why someone would search title for a renovation?
hope that helps...