You would recognize gain and pay tax only on the property you sell.One thought for you as a twist on what you're contemplating.  

I've been contemplating getting my RE license for quite a while as there are many opinions on the books and blogs I've read that highlight specific advantages of being licensed, especially if I want to acquire more investment properties (rentals, flips, and perhaps wholesale deals) in the future.A few unique variables:1) my parents own rentals that they'd like to make sure they pay me as the listing agent if and when they are to start selling these properties in the years to come.

And I can relate--I anticipate leaving the military next summer after 24 years of service and am contemplating a follow-on career doing something like what you describe. 

My wife and I are contemplating the same exact situation.

I don't think any of these homes had AC or heat (definitely not central), so that's another aspect I'd have to contemplate.

I am in a similar boat and have been contemplating reaching out to an 'advisor'.

The question I am contemplating is my next steps.

I am contemplating paying cash for my first property, to lighten the stress of ownership while learning the ropes.

I'm also contemplating hiring a local turnkey operator to try and pull off a couple of foreclosure flips.

I've been contemplating doing this for a while, and finally decided it's time.