This just happened in my neck of the woods:  http://nhpr.org/post/modnadnock-area-real-estate-a...There are many protected categories per Fair Housing laws and I'd strongly recommend you review not only the national ones, but also the ones specific to your state to ensure you're compliant at all times. 

This is difficult to get in my area. 1/2 in. drywall, on the other hand, cut to the right size and doubled up, is dirt cheap.The foam, and you are almost certainly going to need it to be compliant, is what's going to cost you the most if you go that way.

Most importantly, you want to be sure you are operating the entity in a compliant fashion and any quality firm will be able to assist you in that regard.The IRA-owned LLC format does provide several benefits, not least of which is reduced fees over the life of the plan through the elimination of per-transaction and per-asset fees common with many custodians. 

Either way, you need to have good enough understanding of the laws of the type of business to run a compliant business.  

Yes, rent rate per sq foot, but you also have to offset that with extra hallway space which doesn't make money, premium pricing for first floor or near elevator, Large sizes closer to elevator and smaller sizes away, larger sizes on first floor and smaller sizes higher up, ADA compliant hallway/door width/elevator sizes, cart sizes, cart corner bumpers, foyer area, any box/product sales (sqft taken), placement of elevator in the building to minimize distances, structural wall and beam placements,  etc. 

And that's if the buyer doesn't file bankruptcy and delay things.Also, if you were selling to an entity, like an LLC, I'd feel better about your financing not having to be Dodd-Frank compliant.

If you choose to go that route make sure you are compliant with your state lending laws.

I am not quite sure what you mean by "half cement" wall but if it is supporting the house, you need an engineer.If the engineer is going to inspect it, give code compliant advice on how to repair, and have it stamped I think $475 is fair.As a side note, an engineers recommendation will probably be much more involved than what a home improvement contractor may say.

I already spoke to the city and they confirmed I can build a second structure and stay compliant with local zoning laws.

Don't try to reinvent the wheel, this has been done thousands of times, legally, safely, compliant with tax and other regulatory aspects.