We have installed wallpaper behind glass splash backs on many occasions without any problems, the glass usually being attached by a thin beading of clear silicon applied around the inside perimeter of he glass, then fitted the day after the wallpaper install. MOST importantly the INSIDE of the glass be kept perfectly clean on install as even fingerprints will stand out

There are some beautiful patterns around, even from the seventies. As long as you dont clad the entire walls and ceiling in wood panels i think the 70s has some parts worth retaining.

I see wallpapered ceilings a bit in photos. See example. I can't imagine that would be easy to do! An application I did like was wallpaper between dark painted rafters. It was really effective. I don't envy the person who had to do that job. Or anyone who wants to remove it later. In my previous home, every room had been wallpapered sometime in the 80's. All bedrooms, hallway, living room, kitchen, bathroom, toilet. Quite a process to remove! I don't mind wallpaper but I didn't like the ones in that home. I think wallpaper can work really well in homes with a grander scale. High ceilings, architectural trims etc. In smaller homes, a restrained use is more appropriate IMO.

I agree paint may be more versatile - but the right wallpaper on a feature wall with that deer head would be so freaking awesome ! Depending on your colour scheme, if you go with a vintage or art deco pattern, fairly subtle and with a slight texture in it, that'll beautifully offset the deer. And if it's the right choice then you won't want to change it for the next few years anyway. So definitely wallpaper - there's some great 'wall candy' around :-) Good Luck !