These buildings are cheaply built (stick frame, not concrete, you can hear your neighbors doing everything) but look nice to the average renter thats forking over $1,800+ a month for a 1br apartment.

Numbers matter the most, but 1) look at your exit strategy if you need to do so down the road. 2) Get your rehab costs written down in concrete if subbing out to contractor or your numbers are worthless. 3) Include sufficient vacancy percentage based upon the immediate, surrounding neighborhood 1mile or less, when doing your numbers.Plus, as a mixed use, can you get financing or can a new buyer if you sell?

No two borrowers are exactly alike, you need to take steps through underwriting each one to be compliant and avoid financial losses, like fines. 

The reason I ask is people throw around these rules like they are concrete.

If a tenant is not compliant with what is in the lease you send them a notice of non-compliance. we also have a clause that states they cannot run a business from the home I would say this is one of the more important  restrictions when it does come up.

However, I never rent to family or close friends - - imo, make that a concrete policy. 

We had someone come give us an estimate for:Piering the balcony, $14k for 6 piers, and to reslab the concrete. 

It has a detached garage that's insulated, sheet rocked, concrete slab and additional 900 sf, which should also help!

I am trying to put together some concrete and quantifiable numbers that show this- but its not my area of expertise.  

You might be able to save a lot on legal fees by following your state's Intrastate securities laws and skipping the SEC-compliant stuff.