It currently has no handicap units, no Fair Housing units, no handicap parking spaces, and the leasing office is not ADA compliant with respect entry, bathrooms, sidewalk and parking.My question is... what level of accessibility will HUD require for the project? 

Now if the stairs meet the code for access/egress then so be it, but I'd guess that ADA is the issue.

The ADA is NOT a law that governs residential real estate.

@David StumpfI use to teach a fair housing class, so it usually annoys me when people confuse the ADA with the FHA.

Would also like to be able to do a give away for an ADA compliant home for someone that would benefit (of course after through an application and screening process). 2.

It’s the ADA that doesn’t classify them as service animals. 

Will get them before agreeing to anythingIt's for an office - city is asking me to make the building ADA complaint by fix up outside concrete ramp, remove another small ramp, build a new ADA washroom and open up the small hallway

There was no ADA back in the day as it was an afterthought.

Yes - show current photos and state what work is being made in the rental ad as well as photo description (Zillow has photo descriptions). 

You should have photos to post in the ad as people will not apply to rent a place without seeing it first.