Here's a starting place.

I think that better colors would be gray (more or less light, depending on how large is your room) or white. Other colors that match with a mix of black and white would be strong colors as red or green, but I think they are too colorfully to pain living walls. In my opinion the best one is white, although it sounds banal, but it would emphasize your wallpaper and wouldn't condicionate the rest of the decoration.

Depends on the other room that this adjoins with. Possibly gray/silver

Hi Becky I'm not sure what style you are looking for but try www.solidor.co.uk These are the best low maintenance front doors you can get with lots of options on colours, inside and out. We are one of their installers in Colchester and have four on display, if we are near enough pop in, if not just find a local installer. if you are after timber we supply Bereco, again go to their website, not cheap but beautiful. We also can supply Grey windows, not in 50 shades, but in 3, so you can have from light to dark. Anything else just ask. Regards Joe