I'd may send a copy of the rent increase letter by certified mail but maybe not, depending on what all i'd learned so far.I'd always be respectful and positive and stress that the house isn't perfect but my duty is to fix what is broken and their job is to pay on time. 

The house is currently vacant as I'm doing some repairs and posting ads to get tenant in.

what is the fastest way to evict somebody from a foreclosed house?

I've been developing and managing our buildings since the late 70s. 

. - It seems like the property was a duplex at some point and has house numbers associated with it.

The seller signed a contract that MIGHT have said “if anyone that looked at the house while we have this contract ends up buying your home you owe me a commission.”  

I'm essentially investing in one house per quarter.

We went with 2 of the wash towers in our STR and we are our cleaner's favorite house to care for - the love that they can get all the linens clean so quickly! 

Are these related to the air conditioners, or do they control the electricity for the entire house? 

But with the above, please make sure you're not that obnoxious next door house whose light comes on anytime someone walks the sidewalk or drives by in the road.