Operations- tenants refusals, either cull them before they get to you by requiring autopay as an example, document on their application why you refused them, make sure your facilities are maintained properly and no safety hazards exist, etcLLC.

My questions are:- is it worth investing there in terms of the safety of tenants?

You could lease part for food service or coffee shop and some retail space, a small health club, massage. 

Definitely go the legal route here, don't rent out the basement unless you have the OK from the relevant authorities--it's regulated for a reason (fire safety, carbon monoxide poisoning, etc.) and your insurance will not have your back if something goes wrong.

The difference between a safety line and a safety net is that a safety net (your words) can break one line and still hold a fish. 

He has no safety net so I don't think its wise to take the risk because if he did a deal, lost disability and then since hes brand new to REI lets say it takes a while until he gets his next deal I just want to help advise him best!

For the most part its just health and safety items, which are items we should have remedied anyways.As someone else mentioned, biggest thing to avoid is having the house tagged as vacant which the city will do if it sits empty for too long (handful of months, grass not cut, etc).

Common utilities paid by the landlord will be similar if not the same; standard services (extermination, changing filters, snow removal, fire safety inspections etc.) will cost the same.

I do plan to buy a property with 30% to 50% off and have it "acts" as a margin of safety.

Food for thought.