Smaller concern is the plumbing/piping as I believe it originally have galvanized pipes(I heard those are no longer legal), but those were replaced(not sure when), but I think they are okay.

It make sense if you have to replace stuff anyways but not so much if its an upgrade to a working piece of equipment. 

For $20 you can buy a kit that replaces all the working parts of a toilet. ie everything but the ceramic parts and the seat.

I used PBR Construction out of Revere on my triple decker in Eastie for removing and replacing all vinyl, wrapping the windows in aluminum, and replacing decking/railings on the porches. 

Also, don't forget to ask the contractors for suggestions/ways to be cost effective in replacing the roof. 

When I closed they didnt even have keys to give me, I had to kick in the back door(needed replaced anyways).I wouldn't worry about plumbing unless the house is on a slab.

I had to send them receipts of the big ticket items like the roof replacement, windows, replacement and some before and after pics.

Just because a contract died (Could be buyer lost job, neighbor gave an even better offer then backed out, discovered there was a leak in the H2O tank and they replaced it).

For insurance , typically 2 layers , asset replacement insurance + liability insurance = Total insurance .. 

But with most properties, things happen, and this month she had to replace a toilet and a water heater that took almost all her profit.A lot of people in the city use the local insurance carrier that is much cheaper than the big boys.