What level of upgrades are expected for the price rent will bring in?

If so, I would probably save up more or whatever you have to do to get into a SFH now instead of hoping your townhouse appreciates enough for you to "upgrade" later.

I just closed on my first property , a 75% rented (upgrading one unit) four-plex with some good cashflow.

A common one is that the electrical is expanded above code and a panel upgrade with a potential new electrical drop is required. 

The only differences between my house and the one sold are I upgraded the following: a/c system, luxury vinyl plank floors on the first floor and small items such as pull knobs in the kitchen and interior/exterior door knobs.

Seems like you already have a nice system, just upgrade it to get more lead flow in.

My recommendation would be to find a an SFR somewhere between Sneads Ferry and Northern Wilmington and maybe do some live-in upgrades.

I'm not making any structural changes, simply upgrading the kitchen and bathroom.

If I force appreciation with upgrades, should I already calculate the potential increase in taxes into the analysis or just assume that the +/- 5% increase will continue? 

When they upgraded, we rented in to a third family that we really loved.