Home renovations without permits (how much, houses, purchase)

[bearonthejob]

I've been googling stuff for the past few weeks, and this forum seems to be a pretty good place to find DOB info about permits and violations...

Here's my situation - I recently bought a house, 2 family dwelling with basement and attic. I have started doing renovations to some of the rooms myself, but I have not filed for any permits, and I'm not sure which renovations require a permit to do the work. The changes that are currently in process are:

- Expanded bedroom closet by removing portion of non load-bearing wall
- Removed portion of wall between kitchen and spare bedroom to expand as dining room
- Added new permanent stairway to attic space for better access (straight, not spiral)
- Finishing attic wall/ceiling/floors for storage/craft space

The attic originally only had ladder access, but the floor up there is all wood planks, more than enough for a normal floor. The attic height is 7.5' at the peak, with complete open space (no crossing support beams). There were also electrical outlets scattered about in the attic, attached to the floor at junction boxes. The entire house's electrical was redone after my purchase by licensed electricians.

My father is a retired carpenter (mainly does furniture/cabinetry, but also some sheds, garages, and 2 houses), and he has helped me with all the construction so far. But he lives 6 hours upstate, and isn't familiar with city regulations. I'm an electrical engineer myself. I've checked all relevant construction codes and I'm sure everything is up to snuff.

My question is...at this point, what is my best course of action?

1. Can I file for permits for work that is in progress?
2. Can I file for the permits myself, or do I need an architect's office to do that?
3. Can I do the actual work myself, or do I need an architect/contractor for that as well?
4. Should I complete the work and just never let an inspector in the house? (I plan to live here for a long time)
5. Should I complete the work, and try to get an architect to certify the modifications once complete?

I'm realizing now that I should have done this leg work up front, but I lived upstate most of my life, and a lot of these things don't apply there. You can do a lot of work on your house without any need for permits, and I thought all of this work was minor enough not to need them. And since I have the experience and knowledge to do the work myself, I thought I'd be saving money on labor.

I'm concerned about getting violations at this point, and how much it might cost to resolve them. I would like to make everything right if possible. Any opinions are appreciated.

Thanks.