You know, you can always hire an engineer (geotechnical or civil with this type of experience). 

I was told I would have to hire a different company to remove the concrete and then bring the septic company back for inspection.

Is it cheaper to hire freelancers for my rehab as opposed to a GC?

Unless it's super elementary, best to hire it out.

There are about 945 things you can do before hiring a PI.

In real estate I have read "prices are sticky on the way down," which makes sense because it is difficult to sell for less than what you owe, foreclosures take time, many owners opt to wait it out or rent (reluctant landlords), and lenders often have the wherewithal to operate in their own best interest so they get a bpo , buy their collateral at foreclosure auction vs selling below the bpo and in some markets will hire asset managers to light rehab prior to offering their reo on the mls...in an attempt to be made whole.

To be fair, I also recommended that they could hire their own real estate attorney or agent as a consultant on a fee basis to represent them. 

IF you don't have the time/patience/ability to do that, hire an attorney.

Education is not in question like when trying to get hired for a W-2 job.

Looks like your question hasn't been answered.I am locking up about 8 deals a month by cold calling & direct mail - I hired 4 cold callers to generate me hot deals and I take the direct mail calls to my cell phone personally since that marketing channel costs more money.