Just my initial thoughts based on the limited information, I wish you the best with whatever you decide.

I request a credit limit increase twice a year on my main card.  

What are the legal ramifications/liability concerns with doing this without an LLC?

I believe there are limits for the credit, but it sounds good in theory though.

As the owner you are always open to a liability claim, that is why we have insurance.

Is there a certain liability insurance coverage I should have on the commercial property? 

A first-time investor with limit resources to fund the remaining balance of the loan.

The main thing with real estate investment, from my limited perspective, would be to find the niche that best suits your investment style and personality and learn everything about that niche and do it as well as possible while continuing to learn and grow both your business and career.

I've always held title in an LLC name, the main reason being limiting my liability in the event that a tenant or someone else initiates a lawsuit or other action as a result of something that occurred on the property (nothing to do with financing- as you note the bank has the overriding claim).  

Also, is it possible for us to have him convey the deed as a limited warranty instead of a Quitclaim, without starting the quiet title process?