I am beginning as a Wholesaler here and expanding to other areas as I get more experience under my belt. 

Is an LLC the most fitting entity to be under?

Since the borrower is using the primary residence the loan will fall under those regulations.  

If they own several they are obviously investors.Once you get a response from the seller of the vacant house, negotiate a deal to buy it for all cash and get it under contract.

I'm new to the game of investing, but I do have one rental property under my belt.

I am used to dealing with homes that were barely priced under the Freddie, Fannie price guidelines to being in small town KY.

You can probably learn everything you'd need to know for free on here and blogs, and definitely everything you'd need to know by spending under $250 on Amazon.Unfortunately, if you don't have a lot of money yourself I would say NYC is going to be a VERY uphill battle at best, and most likely you won't be able to invest here. 

The property is paid for by cash (clear title under LLC name) and has been generating healthy cash flows.

(d) Whether asserted as a claim or counterclaim, a tenant may recover damages directly arising from a breach of the warranty of habitability, which may include, but are not limited to, any reduction in the fair rental value of the dwelling unit, in any court of competent jurisdiction.(2) If a rental agreement contains a provision for either party in an action related to the rental agreement to obtain attorney fees and costs, then the prevailing party in any action brought under this part 5 shall be entitled to recover reasonable attorney fees and costs.HISTORY: Source: L. 2008: Entire part added, p. 1824, § 3, effective September 1.Gail

Guessing you're desirous to turn your Pittsburg dirt into profits, I think you're on the right track though will suggest strongly that you yourself or someone very knowledgable that you can trust and manage babysits the process down to keys in hand, as I assure you, dealing with contractors and all entities along the developer's path takes an entirely whole new layer of skin and nerve.