If a doorknob breaks or a tree branch falls on the roof or the fence blows over, I really don't need to ask because I know the Landlord will want to fix those things (and needs to, according to my contract).What you really need to do is carefully read the PM agreement to see if they are tacking on additional fees, marking up maintenance, etc.

Growth in the area is through the roof....

Needs foundation, all new electrical & plumbing, siding, roof, etc.  

I am purchasing my second property and was thinking if I should establish an LLC to put my houses under rather than I get hit for it around tax time. 

But of course Realtors want to establish a working relationship where they invest their time looking, evaluating and commenting on properties for investors in the hopes that investor will buy through them.

What questions should I ask, in addition to when the roof and mechanics of the house were installed?

When were the systems (roof, electric, Plumbing, heating) last updated and were they fully updated or just partially?

With that said, how the heck is a cost basis established?

On a personal note, I've only had great experiences using them to find a handy-person where I could see contacting them and possibly establishing a more working relationship for all your properties. 

But once you’ve established your intent you can change the use at any time.