I've had one quote for $7000.00 and my guy charge me $80 to replace the thermostat.

Things like a Nest Thermostat, a garage door that can be controlled with your phone, a nice security system.  

Just installed a Nest wireless thermostat and had a tenant do this at night.

That can largely be avoided by planning ahead to keep it separate as possible,  and submeter or mitigate in other ways when not possible;  like apparently these days you can get programmable thermostats with a 'administrator' mode that will allow you to set a maximum temperature in case you end up sharing with a resident who likes to keep the house at 80 degrees with electric baseboard heat.   

And have semi-managed my own properties from the start with a programmer/software developer background.

I use Homeaway.com to advertise, take payments, manage my calendar ect.I also have an AirBNB account but it doesn't produce many vacation rentals.I have a great housekeeper that I text to schedule my cleaning.I use a Lockbox for keys.I have 2 Honeywell 9000 series thermostats to adjust temp when no one is there.I also just recently installed a camera system so I can see who arrives and make sure no one is breaking in when vacant.Very easy to manage remotely once everything is going.

The CS programme at Waterloo is second to none, best of luck with your studies.   

However, there is only 1 thermostat (control panel) for the whole building.

I am looking at using Operto for my vacation rentals to manage entry, thermostats, and noise remotely.

Batteries need replaced in a thermostat or remote control.