"Buy low, and sell high" works great in the Stock Market. 

Google online savings accounts.Not the stock market...that's using short term funds for a long term investment.

This dog is a deadly threat to society!

Continue seeking rental assistance, but be prepared for that to hit a dead end because the assistance opportunity typically goes away once the tenant leaves.

I suspect that if this were a thing I’d have heard of it by now.These types of credit lines are common in stock trading accounts for the purpose of buying more stock, because there are mechanisms to immediately liquidate the underlying securities if they decline in value.  

Think funds you can back your offer with: HELOC, 401k funds, stocks/bond/CDs, HML, stock options you may have, etc.

Is the large apartment complex dead?

Bonus depreciation may be going away so it may be a good time to stock up on this type of depreciation since it can be carried forward.

I have a 4 family on a dead end street.

I use the rental real estate calculator from financialmentor.com and the one BP has is great too but your limited on the amount of times you can use it if you dont have a pro accnt.When you put all of these numbers into the cauldren, you can then calculate a yearly cash flow amount and cash on cash return.I like most of my Cash on Cash return investments to be more than 12%. 7% is the historic stock market ROI.