If occupied then the buyer and seller come to an agreement as to how that is going to be handled... seller rent back for a certain amount of time or buyer to inherit the tenant with all of the documentation that goes with that, rental application, lease and security deposits.  

Originally, it was created for travel nurses and while their audience has grown, the 1/1 and 2/1 units have the most demand on FF.

All of those are rather strong areas with a lot of pent-up demand for rentals and a strong average household income to make higher-end properties pencil.

I would also consider an on-demand heater that requires less space, no drip pan, easier venting, etc.

If you want to increase the number of bedrooms, you may have to increase the size of your septic to meet legal compliance.One of the first properties I helped a buyer purchase, the seller was trying to sell it as a 4 bedroom, but the septic was rated for a 3 bedroom.

South (Carrick, Brentwood, Bridgeville, Canonsburg, South Hills, etc.) you will find that they are also upcoming markets with good investment potential, also good school districts to consider, with good demand.

My rentals have been in demand, going quickly up for rent.

Now I am bombarded by many sellers. lol

Don't forget that you can negotiate that the seller pays your closing costs, thereby keeping your cash to close at the 3.5% of the purchase price. 

What tools do you use for local market analysis in order to determine current supply/demand for different types of commercial property?