There should be plenty of landlords who do accept SEC 8.  

The seller would not accept any inspection contingencies.

In calling the selling realtor we learned that there was an accepted offer.

You make an offer and then the offer is countered or accepted and within the "due dilligence" deadline, you will have an inspection happen.

Also, how do I accept future section 8 applicants?

He said with a mentor he could have structured these deals better and he wouldn't have had years of break even cashflow.Using HELOCs seems to be a very accepted part of the BRRR strategy many use and I believe still advocated by Matt, so what lessons should have been learned?

It is an amazing deal yet only if the terms are acceptable to you as well. you need to know all of the terms with all of the possible exits that you might need in the future. 

SSN and FICO scores are how mainstream business in the US works, but there's a huge part of US commerce that doesn't operate that way ... and a gigantic share of global commerce that doesn't. 

Is the investor/flipper/rehabber going to make 50 offers a week on the MLS, sometimes getting offers $50k, $70k, $100k off list price accepted? 

In that example I wouldn't expect $75k to be the exact cost of repairs, just an acceptable ball park figure.