Even my mentor at that time and this was 15 years ago, tried getting on the phone with them.

It's your job as a landlord to respond to these things in a professional manner. 

Renegotiating some utility contracts (garbage and removing some on site office paid internet/phone bills) 5.

I have personally known Dmitriy for over 15 years, and my company Marshall Reddick has referred him hundreds of clients since then that have all raved about his service, knowledge, and professionalism.

Cards and board games for older kids but they will all have tablets or phones unfortunately. 

Unsolicited phone call offering to buy a condo I own 500 miles away in Texas panhandle.  

Sounds like you have a pretty poor security system.Even with a good security system, having a tenant provide ID is the first step in a professional screening process. 

Developing and scaling now Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?

What I would like though is to get the feedback of people who have done similar types of partnerships and have learned through experience the pitfalls that I should watch out for when investing using this or a similar model.Because of this post I have already had a phone call with a mentor that gave me some good advice and I am just looking to continue to get some feedback from other experienced investors too.

It is important that you hire professionals who have experience working with foreign investors.