What resources would you recommend for determining if a neighborhood/market is a desirable location for renters?

Are you building rooms with drywall/doors or just wire mesh pre-built cages and what is the optimal size?

Any resources you can point me to or suggest that I review in terms of structure?

As far as information, BP has some of the best resources on the web- think of them as your mentor. 

I recommend that you check out the following resources:1.

What resources were of benefit to you in getting started and learning how to do this profitably?

If I had this resource when I was 20 I would have kept my first little 2 bedroom townhouse and turned it into a rental, the ex husband didn't want to do that (there's a reason he's the ex ;). 

My property manager is a tremendous resource for me when I encounter nuanced buying situations in my local market (San Antonio).If not, I think it might be well worth your while to engage the services of a knowledgeable real-estate attorney to see what your options are. 

Meetup.com is a good resource for those but some of the groups will also post here on Bigger Pockets Marketplace too.

A few great resources for passive investing include @Brian Burke’s book The Hands-Off Investor as well as a membership site called The Real Estate Crowdfunding Review.