To check the proof in the pudding: look at Avantstay's host ratings on Airbnb or other platforms.

Check to see how many contacts a listing has received in X amount of days to see if it is competitively priced.

Check The CE Shop first.

Like David said, I also don't get on here to check my notifications very much.

I have checked with our lender and keeping this home's mortgage will not effect qualifying for our next house.4.

It sounds like the tenant has solid evidence their check or auto payment was received by the wrong party.  

You don't jump out of the plane without checking your parachute.

Lastly, check any shared doors or gaps and add door sweeps or weatherstripping to block sound from traveling between the units. 

We got bank financing on this property and having a local bank doing DD on the property to protect their own money seemed like a sensible way of double checking your own DD!

Here is a list of Construction, Rehabbing & Generic PM softwares that may be a good solution:Construction, Remodeling & House Flipping Specific PM Softwares BuilderTrend/Co-Construct - Home building project management software specifically built for custom home builders.