In general, it works well for me, but here are the things I don't like:- Page loads feel a little slow- No mobile app or mobile-optimized web site available- Unable to build customized reports and graphs- Unable to aggregate data across Businesses (Properties)- Doesn't feel like Wave makes that many improvements.

Any web sites or publications?  

Also, finding one student, even if you have to pay them a couple dollars, to post on the web forums or the sports forums or Greek life... anything that can boost your applicants, which in turn can boost your asking rent.

Do not rely on web-published fee schedules to gauge your costs. 

Is anyone aware of a web based property management system that allows online rental payments with ACH and automatically charges late fees when the rent is paid late?

I have not used investor carrot but in general a good web host can do everything you need.

So it would have some kind of software integration that would create a new key code and issue that code via text or email or a web page to the guest upon check in.

I've been a web developer for more than 10 years now and being an expert on Codeable.io, I see a lot of these questions about hosting.

I work as a web developer as my day job and moonlight as a landlord so I can answer any website related questions you have. 

This agreement is different from many of the Roommate Agreements you find on the web which are more of a "who takes out the trash" kind of agreement designed to decrease friction between roommates.You will also need printed house rules that all agree to (quiet hours, overnight guests, etc).