In full transparency, I have zero real estate experience however would love to meet others who could use some extra help.

You'd get your VA loan paid off, would have it on a traditional mortgage and have an extra 10k-ish to use.

If this is the case, you could move to a commercial carrier and it may remove the extra charges. 

You don't want to increase the rate on $500k worth of loan in order to pull an extra $10-20k for example.

So, there is no extra equity to pull out with a HELOC.

I believe a duplex is worth more to an investor, because when all things are equal between the duplex and the SFH, the duplex generates 2 streams of income, instead of one, that’s an extra door of income to cover partially for when the other is vacant.

Another aspect that made the deal interesting was that it came with an extra lot, which I can parcel off at any time and recover the whole initial downpayment.

., short-term renting a property you rent from an investor), to build some extra cash flow while saving up for your next purchase.

I refinanced the property and combined the extra cash with a large personal loan and some savings to buy a package of 4 properties. 

They'd probably be thrilled to be paying $200 under market and you'd have an extra $5K a year in your pocket.