@ Merkir, that is certainly a lot of opening programs to get in VR.
@ OP, you don't need to re-install ED/Horizons. When the oculus client is running, go to settings and and tick the allow outside content button (cant remember what its called but it is something like that)
Then just start ED from the normal launcher. When the game has started go to gfx settings and set to HMD head set, (again can't remember exact name of button, at work and can't check).
You only need to do these two the first time you set up.
That will let the game run through the Rift, then you can go and play straight away or have a play around with the gfx settings.
Oh and before you launch the game, make sure you have the rift headphones set as default audio device in Windows, just right click on the speaker icon on bottom right of your desktop, select playback devices and set rift head set as default.
The only third party tool I use is Voice Attack as it makes things so much easier in VR, plus I still grin when I can say 'Engage' to start the FSD.

I'm sure there are plenty of tools around to use, but personally I haven't found a need for any ymmv.