I am currently planning on using the VA loan for my first property, and either put the saved up capital towards rehab costs or another property -- so acquiring my first property is at least not entirely dependent on the ups & downs of the stock market. 

That may require or a short sale or not depending on their equity which you may not determine easily without that initial discussion.

Vacancy in those areas usually ranges from 4-8%, maybe higher depending on the time of year (now-March).

@Jermaine WhitePretty much what you already have access to on most websites.The MLS will sometimes have better search functions, but that depends on which MLS you are using.

Depends on the type of encroachment.

General rule (for more reasons than one):Buy and hold rentals=LLC or hold in your personal nameFlipping=S-Corp (although this depends on some other factors as well such as your total profit and W-2 income) It may not be worth it depending on your situation.

If they are interested in terminating the rental contract for $$, there's no issue I can see.A lawyer is your best source of info so call one and pay the $50 for the 5 minutes to be certain if you're going to lose sleep over it.But beyond that, if you are depending on the 3 units rental income to make your payments while you rehab one at a time, then it makes more sense to remove one at a time.  

For example a fourplex; one tenant moves out at end of his/her lease, now you can go in there, revamp the place and raise the rent for the next tenant (obviously depending on market demands and similar rents in the area.)

Appraisers generally are looking at rents and square footage when selecting comps depending on the type of property.

It all depends on the market.Don't be afraid (if you like the agent) to ask for fixed up sold comps.