Are there any questions that one should ask that may not necessarily be intuitive to a new investor looking to do his due diligence? 

The home drawing does not show wiring layout. 

The system is intuitive and easy to use, and they have a lot of options for viewing/tracking financials and other management stuff.

Comps that are most like the subject property in layout, appeal design, neighborhood, same bedroom count and adjusted for different bathroom counts, with bracketed sq. ft. and bracketed sales prices. 

Look at the property finding out what things need to be done to make it a good rental, see the layout.

It sounded much less personal. here is the post https://www.biggerpockets.com/forums/92/topics/468304-roofstock-case-study @jason gines took the time to layout his process step by step.

We need the below:Site plan- Floor plans, exterior elevations, preliminary structural design, building sections, preliminary cabinet layout andelevations, preliminary interior elevations- -dimensional exterior and/or interior renderings depicting the proposed work.

I've thought about writing the letter specifically about the back-tax situation, but my intuition is this will probably trigger negative emotion.

All you need to do is diversity according to your intuition and risk tolerance.

Do you have an existing and demo plan as well as the new layout plan for the skilled trades for them to determine SOW or do you detail the SOW only and your contractors provide the general budget number and the cost gets more detailed as they get into the Reno?