No one will care about you place as much as you, but they are also a go to place for some people who are looking for rentals.I would sell a place if there is frequent turnover and repairs or if your long term goals have changed.

An extra $200/mo. to me wouldn't be worth it to have so many families/people under one roof.

If you send snail mail, be sure to send certified so you have proof it arrived in human hands.Personally, it's baffling how so many people have poor communication skills when we have so many opportunities to communicate in today's world. 

Hospitable is a great app and it's the one I recommend for most people.There are 2 philosophies people follow when it comes to MTR apps.

I'm sure there are some that basically grew up in the business or started way young that are experienced yet under 30 ...

Do you mainly do business in Chicago then?

Disclose, disclose, disclose and just run your business.

I am also looking to educate myself on how the real estate business works in the US. 

It wouldn't hurt to do what some people do and have a home inspector go through the property every couple years.. 

You can close the loan in an LLC so that when you file the 1st year you can pay all payments out of your business bank statements and it will not go against your DTI for future home purchases or refinances.