Here are some I would recommend (presuming you're looking to do buy and hold rentals):Personal Development: The Science of Getting Rich, Miracle Morning, The 7 Habits of Highly Effective People, Be Obsessed or Be AverageBusiness: The E-Myth, The Millionaire Fastlane, Good to Great, TractionReal Estate: The Millionaire Real Estate Investor, The Advanced Guide to Real Estate Investing,Finding and Funding Great Deals, The Book on Negotiating Real EstateI've also heard good things about How I Turned $1,000 into Five Million in Real Estate in My Spare Time and bought it but have yet to read it (as I'm not in rentals).

Text him something like "water is coming from under your door...if you still live there please let me know and handle it otherwise let me know so I can go in and address the issue." 

Or can I just do the LLC and a bank account and separate email address for contacts?

I assume effective age may help distinguish class A and B but otherwise are there any specific items so I know whether I should market mine as A or B? 

She had a hand written note stating she paid $420 with no address or name on it.

Farmers plant seeds by getting to understand and address prospects’ needs and wants.Farmers nurture a prospect by helping her meet her needs, wants, goals, etc.

If possible, during rehab, address some things that will help you insurance wise later:- full upgrade of the electical- full upgrade of the plumbing- removal of any sheetrock, trim, etc with lead paint- new roof- address any drainage/leaky basement issues- hardwire smoke and CO detectorsI know not all will be able to be done but most are cheaper during a big reno and will make you a better risk for the insurance companies. 

Whether it needs to be addressed or not I’m just wondering when they send the 3rd person will they find something else.

They sent in the application and upon reviewing it, his Mom lives out of state, he did not include his Mums employment information or current address.

Ultimately I would let it go if threats and intimidation have no effect.