Much of our data/lists actually comes from services that charge monthly fees for downloads, so I am currently not purchasing lists. 

The Beginner's Guide would be a good book to start downloading and reading here

I would download a copy of the Landlord tenant laws for the State your rentals  so you can be sure of what guidelines you as owner are responsible for.. the PM is under your control and basically, and everything they do, you are responsible for..4 units all at once ..

download your landlord tenant laws for your state,, it's your best go to for info.."

For some reason I only got "Certificate of Formation" when created the LLC.The website is only offering ordering it over mail ... do you know if there is an option to got it emailed or downloaded?

Download the landlord tenant laws for this state and you'll have all your answers,, like you said each state is different so find out from the correct source.Your notice of non-renewal / vacate would be in those regulations,, but ususally a month to month term only required the same for notice period,, given in written form, mailed and copy posted on door.. prior to the 1st of the month.. for a full 30 (1months) day notice period.

@Michael Sato, I've seen the Path to Purchase and have read through their Getting Started downloadable PDF.

I would recommend you start by downloading your landlord tenant laws for your state..Then set your rental criteria,, credit score, income, (= to 2 or 3 time the rent ), occupancy limit per bedroom size of apartment... no cosigners,No pets,, no smoking,, what ever..but it stays the same for everyone.. 

It's a business, if you find some is abusing it financially (not paying rent) or physically (damages),, you push the envelope and write up a lease violation and if necessary evict.. doing regular inspections let's you bill tenant for undue damages when they occur.. and yet still have the deposit left to help when they leave.If you haven't yet,, download copy of the landlord tenant laws for your state.. 

SEC...They have pdf download of city streets and zoning.