Part of me thinks it is unnecessary due to the safety and culture of the neighborhood but at the same time, I am aware that it is opening me up for the possibility of a lawsuit. 

It may be too late and unnecessary since you're already far enough into this deal.

It's just an unnecessary risk.

However, we (my parents and I are the owners) noticed that they are using the HVAC in excess and using what appears to be unnecessary electric (TVs and lights remain on even when not in use and air conditioner is running constantly).

Look for multifamily, because condos, like co-ops, usually impose a "flip tax" (not really a tax per se; it goes to the building reserves). 

My question is when or how much should I start investing in a Roth IRA to start the compounding effect while not imposing on my potential real estate investing money?

And it's unnecessary to tell them even if I was using the free version.I did share these comments with them and I hope they take them seriously.

The Net Investment Income Tax is imposed by section 1411 of the Internal Revenue Code.

Hopefully this will get better as time goes on... or eventually becomes unnecessary.  

Meaning that they don't have multiple late payments, cause damages to the house, cause unnecessary wear and tear, exceed the occupancy limit, breach the lease in other ways, etc. .