Your RE agent should be able to advise you on this, but SOP in this sort of case is to get a licensed contractor in for anything you think is major (ie, electrical) and give you a bid on fixing it how you want it fixed. Then you can decide if you want to have the seller fix that stuff, or if you want a price concession (better option in most cases) sufficient to pay for the work. The seller, of course, can refuse to do that.
If some of code violation stuff (stair tread, in particular) isn't fixable, obviously, that could be a problem for using it as a rental.
-W