There are certain restrictions on IRAs make sure you check with an IRA 3rd party before jumping into anything.

I have read that it is very difficult/near impossible to issue conventional mortgage at a 4.5-5% interest rate if you are incorporated, due to Fanny Mae & Freddie Mac restrictions. 

It depends on your local rules but splitting a parcel can be a major pain and the locality might not even allow it due to zoning or setbacks or lot size restrictions. 

(A)   In addition to the duties imposed upon Tenant by this or other provisions of this Lease, Tenant shall at all times maintain the Premises in good condition and in reasonably clean and safe manner.

Some states (jurisdictions) restrict the amount of security deposit you can obtain.

@Andrew Wilson a couple of things here:If you are using a Fannie/Freddie loan (those are the ones with the lowest rates on a 30 year fixed) then the cash out limit on a 2-4 unit property is 70%If you are seeking cash out in the first 6 months, Fannie/Freddie loans will have some pretty detailed restrictions. 

The HOA usually has restrictions that don't allow renting or that delay when it is allowed. 

There are many folks who will tell white lies in this direction which I cannot promote so think being honest is the most sincere way to generate a response without imposing on them.

Even that may be restricted by the lender.

The three opponents were pushing for more a Denver-like Airbnb law that restricts STRs to only your primary residence.