Going full bore on them will hurt their feelings and may cause them to move.2) Do NOT get involved in disagreements between tenants unless they are willing to file a police report or one of them violates their lease!

Anything $2500 or below can be deductible via de minimis safe harbor.Higher expenses need to be capitalized.You can also do a Cost Segragation Study to capitalize some items quicker based on life expectancy. 

You can find more info the group studying the issue here.

You should join LP Forum and they talk about this 24/7, this is the topic that I really get very bored of.

That's all the location study and analysis you need.

Thats generally what studies pointed out in the past as the effect of rent control.

Besides this, rather boring, pastime of writing code, I also happen to be extremely passionate about real estate, more specifically multifamily and I decided to launch a new project to develop an MVP of software solution that is tailored to the needs of property managers. 

What did you study?

Stuy after study has shown that the less a person injects into a deal, the less likely they are to pay the deal back.

You can read the forum and create a list of the 30 most common problems, then study how to handle them and develop a plan for each in less than a year.