Leave the brick inside the fireplace but maybe tone it down a little. Get the rest of the brick plastered over, including the little display recesses which are very dated. Change the tiles to slate (still could be tiles to make it cheaper) and it would look so much better.

Liking the eclectic look! You do have a fair amount of furniture in the space, but I think with the look you’re going for it can work well, its just learning how to work with it. I don’t think it looks cluttered at all. At present, besides the furniture, the room is fairly simple and so your eyes are mostly drawn to all the furniture. I’m thinking if you add in some accessories here and there, it will help to create interest and change the focus. It’s a great way to tie everything in together without using an area rug. For example, adding some feature wall art above the sofa, whether that be one stand alone piece or a cluster of a few. Or how about adding a nice red throw over the sofa to tie in with the red chair? Adding plants/flowers on top of furniture are always great options as others have suggested. Your oval footstool is a lovely piece. Maybe you could add a tray on it with some accessories on? In terms of creating more storage, maybe you could have a think about open shelves and find some interesting ways to display your items. But the bookcase is lovely too! I suppose it really depends how much storage you need. They’re just some initial thoughts. I won’t be offended if you don’t like!

Yes you could put mirror in front. It might be a bit disconcerting to catch sight of yourself when you look out? Clematis montana is great when is in flower but doesnt do much for the reast of the year, it can get huge and after a few years the stems will be very woody and not very attractive, so I would suggest planting it a way away from the wall so it doesnt take over. Could you post close up pics of the plants above the wall and the planting area?

I suggest you to use wall pottery decoration for general all around the house, also you can use frames, plates (new or old ones). For utility closets: they are build with old fashion way: the wood shelved directly mounted to the plaster wall. Just transform it with built in closet. All the inside can be done with plywood, preferbly pine , veneered: it will make a marvel. Painting will not make the same effect as wood. Wood has magic, it penetrates your soul. When you use plywood , that makes you environmental friendly too, plywood is treated wood, so it never incorporates bugs and stuff, it can withstand humidity with ease. I agree on door style change as other advisors have greatly shown beautiful examples.