Ok, I don't want to read 41 pages
Which device do I buy from where?
What do I install on it?
That's really almost like asking how long is a piece of string.
If you've got some technical ability, I'd go for a Raspberry Pi 3 (you have to buy the board, a case, a power supply and a 8Gb micro SD memory card). You can get it from RS Components:http://za.rs-online.com/web/generalDisplay.html?id=raspberrypi
Then you can install LibreElec on it:https://libreelec.tv/downloads/
Installation instructions are on their site.
Once set up and connected to your WiFi (you would need a USB mouse, keyboard and a HDMI monitor or TV for this), then the fun starts as you need to install some plugins for Kodi (the media player that LibreElec boots into). Thare are lots of different opinions on which plugins etc to install. I installed the following (just google "kodi " and plugin name to get instructions on how to install:
And then lastly if you've got an Android phone, install Yatse as a remote control app for Kodi (so that you don't have to use the mouse to control the media center). For iPhones there is a Kodi Remote app, but it sucks when compared to Yatse.