I think here it looks a little bit tacky. Sorry but I would put other colours on the back wall, blue for example? Otherwise it stands out a bit too much.

I'd go for a tall slim book shelf. TV is hard to work out without a plan of the room! If you want to sketch something I'll happily take a look at it.

Without knowing the dimension of your room it's hard but I would suggest the following: Colours: keep it neutral, try not to choose colours within the yellow spectrum. Although you would think it would make it feel 'warm' they also have a tendency to make it feel quite dark. The room is too small to do anything majorly bold with your walls. I would be tempted to choose a slightly off white colour and use your pictures and a big colourful rug to bring colour into the room. Orientation: put your TV in the wall above the fireplace. Your sofa under the stairs and get two smaller occasional chairs on the wall the sofa is currently on. Also put your large mirror on this wall. The armchair you have could go where the TV is and be used with the standing lamp as a little reading chair. Windows: slated wooden blinds in brilliant white would look great. Lights: change the green to match the chandelier light, the rooms not big enough for two different lamp shades. Or at the very least a different chandelier? You need small tables with lamps on dotted around. Your pictures are hung a little too high to the ceiling. You might want to try grouping them together a bit more. This is just what I would do, but It's a pretty little room, it'll look nice whatever you do.

depends a bit on if you actually use it for fires or not, but in essence you can either paint it by hand which can give very hard wearing finish but is hard to not get brush strokes, or you can use a good spray-paint which will give a very smooth finish (Especially if you want a gloss finish) and you'd just have to mask it up. For either you will only get as good as the paint below it so make sure its smooth. If your going to use the fireplace the centre parts would need a high temperature enamel, or a humbrol enamel will work as well but its very small pots but good if you want a satin colour. Personally I'd go for a very dark grey to match the hearth rather then black as a lot of detail can get lost in black.