Hello Stefan
At first. Welcome to the OH Community 
As Udo pointed out already: If you new with OH. Start with OH2, otherwise you have to learn some things twice.
Yesā¦ you have to buy them. Most of the bindings use some APIās of the Bridge/hub/whatever 
so you Need to have These Units.
Donāt worry about Linux skills. Since @ThomDietrich have build āopenHABianā, an Linux Installer with openHAB for RPI, you donāt Need to know Linux in deep. What you Need, you will learn by doing. You can find Information about this installer here
I recommend you an seperate machine, because the longer, the more you Need it up ānā runningā¦ Please take a look at the recommendations reagrding SD Cards at RPI.
It sounds like you are an perfect candidate for zwave. Youāll find presence sensors, RGBW Controllers, Dimmers, Switches and much more, which will fit your Needs.
Such Projects could get very complicated very fast. I recommend you to start with some Basics, build up your skills and extend your Project step by step.
youāll find many bindings for your Needs (Samsung, Fritzbox, Geofancing <== your early-warning-system, Kodi)
Actually, I plan my own house renovation, so I can feel with youā¦
Enjoy!!
Michael