Depends how high your ceiling is ? You can get 8'x4' pre finished sheets of various wood /wood effect - back in the '90's I did a similar thing out of MDF to hide a horrid old fireplace ! ( that was wallpapered after ) it was in a rental property - but offered relief from the eyesore and was removable when the lease ran out ! If you are in the south of UK there's a company called Lamco in Poole who do fab things made to measure - I'm sure they could make one - but I do know they are incredibly busy - so might take a while !! Long flooring planks might be easier as pre finished and 'settled'. Good luck with it !!!

Do you mean wood panelling? It looks good in pale neutrals from off white to grey-beige like Elephants Breath, but colour choice will depend on how you will be decorating the room - is it modern or traditional? Panelling usually suits a more country style. I’ve seen panelling painted in dark grey and deep blue, but I think it looks much better in a paler colour.

will it Matsch a grey floor? or maybe a nice color instead? Blue note? and than what kind of new sofas?

https://youtu.be/S5G1NG1UpfI This is one of the videos that I watched (over & over again). It briefly covers the measurements from about 1.50mins into the video. It’s basically; measuring the width of the room, subtract the total width of all the spaces/boarders then dividing it by the number of frames you want. I think anything from 600mm onwards works. Some go for slimmer, others go for wider, but again it’s whatever is works for your room & you. We ended going for two slim/side panels (I think 650mm) & a wider middle panel (I think 2100) - just because of the way our headboard. All the different panels look great. I personally wanted to add more depth on our wall so I decided to use 90mm thick MDF boarders (but make sure you have the same thickness decorative panels/frame), instead of just putting the frames on the wall. With regards to tips for the measurements, I saw / read somewhere (probably Pinterest or YouTube) that if you are going to have a bottom or lower rails / section (then your lower part should be at least a meter from the floor - I think that’s so chairs don’t scrape the rails. Regarding width I think whatever looks best in your room. Again what works best for your room. Ps I would also add that from a personal prospective leaving the same amount of room at the top/bottom/sides makes it look better. Sorry if any of that was like teaching you how to suck eggs. I’m very excited (perhaps too excited)😊This is literally the only thing that I’ve made since secondary school apart from a airing cupboard shelves. Normally I’d pay for someone else to do it. Hopefully you found one thing helpful. Good luck.