Without these tools, you'd have to do a lot of manual data collection and copy/pasting of comps/data into a spreadsheet for every property you analyze, was kinda the reason for building this out.

I would just use rentredi to screen tenants and collect rent payments. 

They have lots of little fees built in, so I'm curious if those are also on the back end as well:Return to collect rent again Fee x3: $30Phone call with tenant fee: 8 minutes. $5 + .50 per minute.etc

There are a lot of hungry rookies out there that will collect a "Broker fee" or have you pay for a LOI (letter of Intent) and it's nothing but a piece of paper.

We will do over $750k this year in revenue form our Airbnb portfolio and that's because I took a leap of faith in myself to start an Airbnb arbitrage business 4 years ago.  

So, likely the HOA would not even collect any money unless the mortgage was small.

I am now summarizing the key points for managing rental properties to build my systems before launch ( I am strongly considering Rent-Redi software) but I am wondering how I would use this software for client's properties when collecting rent, holding deposits and the like.

Haven't heard that term used for data collection/skip trace.

I guess you could collect an illegal commission if the sellers and their JV partner were willing to pay it. 

You can only collect rent from one person at a time, so if the old tenants rented it until July 31, but move out (and have paid rent) July 15, you could (with their permission) let the new tenants move in July 21.