Also have a conversation with the main city building inspector about any possible problem or if they are aware of any problems at that address. 

.- I haven't gone through my actual due diligence period yet BUT I will have an inspector go through and I will then get my actual estimates off that inspection.

My next recommendation is to contact an experienced building inspector and find out their busiest areas and what you could expect from them. 

I walked though using a home inspector last week and no damage to date. 

Also  I think the reason why he hasn't signed on the offer or any offers for that matter is because the tenant in D has not been cooperative and he is worried the tenant will not allow the inspector to get into the property to do an inspection on the unit.

If you are concerned you can hire a private inspector.  

Some inspectors won’t inspect houses of the neighborhood is too bad.

But will see what the inspector has for me:-) Thanks

(I've been friends with the inspector for 3 years and really trust him) All of the mechanical's, hvac, etc.

The inspector said the house needed a new roof 5 years ago when I bought the place…When I walk on the roof there are areas of clear rotting in the sheathing under the shingles, it’s spongy as if there has been moisture intrusion and rotting of the sheathing…The roof is bowing in some areas also, and has a couple of curled shingles.