a lot... a ton.... off the charts.... not even close...Check real comps in area

Start checking Zillow, Redfin, etc., for both rentals and sales prices. 

A contractor can help yes when it comes to looking at it and telling you how much or what you be looking at if you want to upgrade or fix something visible but you need the inspector to check out the roof AC and plumbing thoroughly despite what it looks like in person I’ve seen mini jacked up ceilings.

I'm a licensed realtor so I have access to the local LMS, I check out public LMS sites, Facebook, Craigslist, and the few deals I find are gone far too quickly...I work a full time job and do real estate on the side.

d) set mouse traps and check them often (not a set it and forget it option and dead animals can stink, hard to check traps in a crawlspace regularly no?)

If you go the new home route, check the rules on resale and if there is a right for the builder to purchase it from you or a minimum time before you can sell it. 

check your local laws as a few people on BP have posted that you can only do evictions for unpaid rent in some areas.

I also open up Airbnb and/or VRBO so that I can cross-check the properties. 

Even with $0 down I may be able to cover the mortgage with BAH from the military but then I'm concerned about all the other costs (CAPEX, PM costs, regular maintenance, taxes, etc.).

If Airbnb has confirmed these are Service Animals I wouldn't make any waves and see if there are any issues after they check out.