Hypothetically if I win a bid, then would I be able to utilize a HML for any possible repairs now that they'd have access to inside the property?

To build that kind of portfolio you will also need help with financing, locating, inspecting, repairing, etc.

But how can we draw a line between repairs and replacement?

It is almost as hard to buy a fixer upper at a price that will cash flow after repairs. 

If the property is bleeding money every year from repairs, maintenance, or turn over you'll never get ahead.You can tap equity with a HELOC (challenging right now), cash-out refinance into a new loan (much higher rates), 1031 exchange, or sell (tax hit) but the numbers and property condition need to guide this decision.

I got free repair estimates (inspections) from two roofing companies.  

Roof was flashed and repaired in May.

Is this a low number for both vacancy and repairs? 

There has been such a journey with renovations and the person repairing the property, but hey!

Those repairs will never get done.