Thank you Carl...yes....these additional taxes are what I am referring to. 

You would have to check out zoning regulations in your area,Where I am, I have to get a variance in addition to approvals if the area is not zoned for two.

Additionally, if your partner has $0 funds and you have 100% of the funds that would be used to purchase the home, you can use your funds as well and not have to count them as a gift, so long as they are in your account and fully seasoned by the time you buy the property. 

Ask them how many ghosts there are, because they're additional tenants and they'll need to adjust the rent to pay for them

My duplexes do receive an income approach to value when appraised, but because it is residential, the comps carry much more weight. 

In addition to any specific brokerages in the area (Stafford, Va and surrounding counties), any advice on terms of working with a brokerage? 

I agree with Corby.if it is cash flowing well, why get rid of it.I am growing my portfolio by adding rentals with occasional flips on properties I don't think are well located or have some good cash return on them for funding additional rentals.

These are professionals with additional training and a stricter code of ethics.

Oh, and I haven't taken into consideration the write off of the additional interest on the cash out refi. 

I am going to use Robert Kauffman for an addition on a SFH I recently purchased in Tucker.