If you're looking to manage your own homes and perhaps start a property management company, it's a great idea to get a job at one in your area, as you'll gain a lot of useful knowledge and can ensure that you handle future situations legally, correctly, and efficiently.

The data does not belong to the Landlord, period.Even if the Tenant gives written consent, the Property Manager cannot share the data.

I'm 31 and work in data and analysis at an advertising agency. 

It gives you a paper trail and all of your data in one place.

That will ensure you are making very large mistakes that will cost something like a $100 of whatever just cause you didn't think to add it as a negative. 

And if I'm not in a major MSA, should I use the data for the closest major MSA?

Whenever you are buying a property out of state you should do a few things to ensure it's as smooth as possible.

Right now, I've been putting in data from Zillow and Trulia based on recent sales and current listings. 

I would ensure your buyer is able to get confirmation from their lender that it is not a disqualification so it doesn't creep up during underwriting.

I am looking for an attorney in the Aurora or Naperville Illinois area to review my lease to make sure that I am managing the property within the local laws as well as to ensure that the lease covers me if I do run into an eviction.