But, VA is the only "owner occupied" loan type that you can actually refinance after you have converted this to an investment property! 

I’ve had a handful of STR property owners that are looking to sell. 13 units in total.

The main difference is that you don't borrow "money ", but instead buy the property from the lender over 360 payments, and the price of the property is marked up - this is the "profit" they charge.

@Haneef PorterRecommend you first figure out the property Class you want to invest in.Why is Property Class so important for investors to understand and apply in their investing strategies?

I'd like to not "find out the hard way" if one of these sites are not a good match for me.The ones I'm considering are Propstream, Property Radar, ListSource, and PropwireSomething to note, I am looking to return to doing some wholesale deals, using criteria such as absentee owner, out of state owner, tax delinquent, vacant, liens, and pre-foreclosure..

A good PM protects your monthly income and your overall property value.A skilled property manager will protect your property, income, time, and sanity.

Because the Property Class dictates the Class of the tenant pool that the property will attract.

Given your skills, you might consider value-add properties, BRRRR (Buy, Rehab, Rent, Refinance, Repeat) strategies, or even house hacking to maximize returns.

I would like to use the equity I have built up in my current duplex to purchase another investment property.

@Devin James I'm not currently doing it, but I've for sure toured some properties in my market that I think would make great candidates.