I use Locative for geofenced presence detection. They have an iPhone and Android app. It works really well for me. I tried using other presence detection methods such as wifi detection and door lock codes but couldn’t get an acceptable level of detection. iPhones sleep the wifi after a timeout period and door codes didn’t work if someone is already home and the door is unlocked.
I use a combination of zwave and insteon wall switches to control existing lighting. I like this one from Innovelli https://www.amazon.com/gp/product/B076LS3SLY/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
I don’t like the wall plugs because of the extra effort involved in turning it on manually. I’m kinda lazy that way.
I can’t offer any advice on the entertainment system.
I can comment on the thermostat. Avoid Honeywell and any other manufacturer that requires a cloud based solution (that’s also good advice for everything else). The Insteon thermostat may meet your requirements if you have the Insteon hub. It doesn’t support my dual fuel system so I can’t comment on it, but the binding does support it. I use Venstar t7850. It does not have a native binding but can be controlled using http get and put commands like these
Good luck and have fun! You will find the Openhab community to be very helpful and welcoming.