Gutted and replaced almost everything.

There are multiple reason why that is a bad assumption (that investor could be insuring that property at Actual Cash Value vs Replacement Cost, that property could be with an insurance carrier that no longer writes multifamily and the policy is grandfathered in until it switches ownership or that property could be under insured from the previous owner).  

We will be replacing flooring, cabinets, lights, vanities, toilets, paints, cleaning up the exterior, addressing the foundational needs and more!

You own the property and the residents are replaceable if needed.

At least in their markets, once the home is depreciated out, they can always replace or sell it in place for just the lot rent.

As you know rent is quite low (median in Milwaukee is about 1,200 for a single family) yet you have the same infrastructure to maintain: one kitchen, one bath, one HVAC, one water heater etc - cost of replacing a water heater is the same, no matter if your rent is 700 or 1200 or 1600 (which is our typical rent for a SF).Income (rent) is a function of size: bedroom and bathroom count as well general space meaning square footage.

But there is no replacement for your own education that you HAVE to have to really understand what you are doing with your money. 

Can anyone recommend a structural engineer/contractor that won't charge an arm and a leg to analyze?

Roof will need replacement in the near future.2) EXTERIOR: - (including siding, drive/walk): No problems found.

I am replacing a few floor decking sheets, replacing the entire bathroom in one tore walls out put in new studs, tub, toilet, etc.