Should I wait this one out or make a realistic low offer and see what happens? 

You can’t go long periods of time especially in low income areas . 6 months is plenty long enough to destroy the inside of a house if left unchecked .

Ther eis no possible way you can get ahead with a score that low.

Again, this seems very common in the outer boroughs of NY for low income families, and am just curious. 

For financing, am I on the right track with who I've talked to already, or do I need be someone who throws leverage to the wind and simply keep a fat wad of cash for PP+Rehab costs in my bank account until it's time to use and simply skip financing all together?

Despite the extremely low LTV ratio, multiple bankers I have spoken with, keep telling me that home equity lines of credit can only be levied against a primary residence, and not against an investment property, or portfolio.

In low rent markets a rough estimate of the expense, not including debt pay down, is 50% of the rent.  

If this is something you want to do, make sure you go 100%, if not, then the success rate is very low for anyone looking to get started, but this is true for any business you'd like to start.

I have seen some with short programs with low/affordable tuition. 

Your capex and maintenance is likely low. 550 renters are gonna be tough on a property