We have done houses and cash for office.

@Amy T.I order my locksets in bulk from MFS supply...$8.00 for a combo set...way cheaper than home depot and better than spending my time trying to rekey an existing lockset...

There is a big caveat to that though, which is that (1) I haven't entered into any LPs myself, and (2) the clients I work with are large real estate investors not using conventional bank financing.However, I did make loans to LPs as a bank officer prior to practicing law.

Can you go to the local city office and ask about the invoices?

You will need to contact your local buildings department office for those answers. 

Is Brad someone from an office local to you, though?

The STR has higher expenses than LTR, so this is no where near as much cash flow as getting $15K/month for an LTR but it is significant positive cash flow.I suspect the rent as a LTR will be between $5.5K and $6K per month but we have done a rent survey yet in part because I am anticipating the LTR rent may fall due to the increased supply of LTR units. 

These are not allowed due to the zoning and since the property is in proximity to the airport which places density requirements on the parcel.My plan is to move into the house and fix the other building up into office space to rent out. 

I have a few attorneys that our office highly recommend that would love to help you!

@Andrew Mercer its highly unlikely that you will be able to add another unit so before you start anything research with the local code enforcement office to check if there are occupancy permits for the existing 3 units and if a fourth can be added.