I would definitely paint out timber frames, they in themselves become the feature if you don't…..and I would hope you mean a soft grey! To "hide" skirts and arc's (I renovate and sell for a living) I do them the same colour as the walls but in a satin finish…..you could do semi gloss….a water based enamel works best. Make sure you prep them well though, either a good sand to rough up, or something like ESP. I always thought rule of thumb for a feature wall, paper or paint, is the wall opposite the greatest light source, ie. the wall that gets hit with the most natural light. Failing that, I think it would look lovely on the alcove/bay window wall and do the inset of the alcove/bay window in a contrast….say a soft version of the pinkish hues in the paper??? You seem to have some substantial pieces of furniture, and a piano, so doing the other walls would compete and look overbearing to me. Unless you are going the whole Regency style embossed paper/stripes/pattern everywhere…………...

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

Can you provide a picture of where you're planning to put the paper vs the paint? I think, myself, that wallpaper should be continuous along the length of the wall, unless there are architectural features that break up the line of sight.

Having lived in the UK, wood chip paper deserved its reputation as the most difficult paper to remove, but there will always be patches that are a little more stubborn! Is your steamer a wallpaper steamer with flat base and 'ledge' to sit against the wall, or a general 'steam off into air' steamer? I found my wallpaper steamer brilliantly effective, and brought it back with me... Friends who borrowed it were so impressed, they wanted to buy it off me. You will find this method works on all paper types, including flock and vinyl faced. First, lay a plastic groundsheet. Mel N is right - score the paper all over (in smallish diamonds or just randomly) with the corner of a 100mm wide metal paint scraper. The closer the scores to cut the surface of the paper, the easier the stripping. Working over 5-6 (steam base) areas, place steamer against the wall, allowing time for it to penetrate the edges of scores each time, then come back to scrape with the metal scraper from the first area, then second etc. This gives the steam time to seep in. Repeat. Clean up wallpaper scrapings from the floor regularly as they will be sticky and messy. Finally wash down the wall with sugar soap to remove adhesive, open windows for drying and prepare your walls as usual.