The first book I would recommend you read is rich dad poor dad, it would help you get your mindset right.

Communication is through text messages, I don't take phone calls, unless it is a call we have scheduled.

In use it for rent collection, expense tracking, I also have my tenants use the chat so the communication doesn’t get lost in my email and text messages.

If not, it may be time to investigate other property managers and find one that's willing to educate you and communicate more clearly.

In addition, we also have investors (currently, about 20 active and 50 potential) and we're looking for a simple tool to keep in communication with them as wellDo you have any suggestions for something that's cheap, easy, and fits these criteria?

I've read a few REI books like the book on investing in rental properties, how to invest in re with no and low money down, rich dad poor dad, buy it rent it profit, and about half of the millionaire real estate investor.

Feel free to PM if easier to communicate.

While in the process of testing several online business ideas, I read Rich Dad Poor Dad, and I have been reading and listening to everything I can get my hands on related to REI.

It probably doesn't hurt to frame communication with the tenant as if there was a 3rd party involved in decision-making. 

Your agent should communicate with you quickly, often, and outside of normal business hours.