@Mary Jay - Dustin has good info.
I can't recommend going into the office enough. I did a small bump out of 12' on a house and the rules required going through a board of review because it was within a certain distance from a hill. That would have added 3 months plus a couple thousand dollars in fees. I walked in, talked to them and they waived it, approving my drawings and permit on the spot.
If you get the permit approved, all you have to do is follow the steps along the way, get each box signed off on (as Dustin says, one for framing, one electrical, one plumbing if applicable, etc). When all those boxes are checked or N/A, you call for final inspection. That's just the last formality to make sure your smoke detectors and CO2 are installed, cover plates are on, fixtures are in and you didn't change something from the last inspection until then. They sign off on the occupancy certificate which allows you to officially live in it. So don't worry about them not approving it after you do all the steps. There would have to have been some major change you did or didn't do. And then they would just give you a remedy on how to fix it.
For sure get an estimate on permit fees before deciding to go forward. They can be cheap or quite expensive. The other issue is if you're on a septic system, they look at each bedroom to determine the load on the system. Adding a bedroom usually means more people. If your system is old, you'll be in for a replacement in the $8k+ range.