They also have various home improvements (replacement windows, repairs to rotted truss in roof, bracing, new decking and shingles in the area among other things) that have no permits.

Here it's more shingled roofs. 

My estimate is about $30,000, and I agree with you that even that is probably too low.The largest seems to be a recent self-done roof replacement with buckling shingles only months after the fact.

I do this for any vendor I use each year, as I carry workmens comp on my properties for myself and workers I know aren't covered themselves. but if I can prove my vendors have insurance when I'm audited, so my insurance agency compute rates in my favor, because vendors had their own coverageAs far as lien waivers, it's good practice to have anyone that worked on the house sign they have been paid and a lien waiver is used for that. 

Shingles were in decent shape but a little unsettling- to have to replace an entire roof would be devastating.

If it has lifted shingles, patches etc, in such cases the options are basically; fix it (new roof etc), exclude wind/hail (fire/lighting only), or NOC.

I suspect that the house is a wood frame or possibly covered over asbestos shingles. 

:__________________________________________________________Yes ____________________visual inspection of components conducted with no notable defects no water was introduced due to intact winterization _____________________________________several shingles were missing or out of place on the roof, no water stains inside nor in the attic Roof: Damaged --Other: N/ARoofing in acceptable condition?

Building is 1968- will have to find out about lead paintPitched Asphalt Shingle Roof with aluminum gutters, Ill have to double check but think its 5 to 7 years old.Separate meter for electric but owner pays for heat (Oil-- not sure conversion gas is worth it but option is there)Good question about wiring, i would've never thought of that..I would assume I want it to breakers..

And @Gail Kaitschuck I will be adding some supporting 4x4" posts and sistering the existing roof trusses with 2x6"'s, along with getting the roof done (stripped and re-shingled).