once for all! small flat reconstruction / remodeling

Briefing

Hi all of you! I welcome you to my flat.
A bit of story of this flat.... I live here since 8 years. It was a very old style flat, and I have been doing incremental modifications. Before it had 3 bedrooms, and a living room and a long corridor. I first removed the corridor (attaching it to the living room) and 3 years later I removed another wall creating a huge space. Even too big. I have tried different configurations, and, for example having the sofa against the wall creates a huge empty space in the middle that I do not like. You can see in the pictures that I have invested very few in furniture.
In the floor I filled the gap with limestone blocks. I like how it looks like, but I am considering also removing all the floor and putting it new, or putting some parquette over the actual on. Will it make a lot of difference?
Now I will start with the WC, professional painting of all the walls, new doors in the bedrooms and bathroom, the furniture of the living room, and in a second phase, the kitchen and the main bedroom, and the cupboards but I want to have NOW the final solution in order to foresee some of the changes I might need in the future. You will also see that my interior  skills are not the best. I am looking for a union, for a unified design of the house, where I can feel comfortable. I am not considering constructing new walls unless the pay back is really big. IF then only demolishing (kitchen/living room), of for constructing a sliding door (WC, kitchen).
I marked the modifiable walls in red.
I am looking for appropriate distribution of spaces and a good handling of the incoming (few) light, figuring out which furniture could be best for the entrance, living room / dining room and big bedroom and were and a complete remodelling of the WC and kitchen
Entrance
+ Living room:
VERY HIGH PRIORITY
-The entrance is also a bit spartan (sad).
- Lack of light. It is a first floor, and it only has two windows to the outside. The amount of light is limited even getting rid of some walls.
- As you see in the photographs, I do not have a TV since 5 years. I would like to have a "not TV centred" living room. I like reading, and I like the image of books in my living room. We have the TV cable at home and I am thinking on having a AndroidTV or installing a flat screen in the future to see films now and then. A projector could also be a solution. But as I say, it should be a "not TV centred" design.
- I nearly always have the radio on. I am also thinking on buying a good stereo system, with high quality loudspeakers. I need to know the position of it.
- I would remove the "computer corner" to substitute it by a laptop. For that I would need to have a "natural place" to have it.
- The heating tubes in the living room DO NOT need to be hidden. I recently removed the old bulky ones. That is why it looks like that in the photos. I like them as they are. But that space could be used for a furniture, or fixed table, or nothing.
Up to you.
- I would need some (not all) CLOSED cupboards in the  living room and dining room. Tidiness is not one of my first characteristic.

*Bathroom (complete remodelling)*
VERY HIGH PRIORITY
- Is rather small. I want to change the bathtub with a shower. I (for sure) think that a sliding door is a must in the new design together with a gibberish like wc system.
- Consider also the possibility of changing the bathroom to the entrance. I is only a possibility, but rather expensive to change it. If the payback is big, I would consider it. I have analysed different distributions and the gain is not very big. But who knows!
*Bedroom*
 I don't know what is the best distribution. The actual wardrobe is rather limited for two people so I might need some shoe cupboard or drawer, but where? Possibilities to easily enhance storage space?
*Kitchen (complete remodelling)*
LOW PRIORITY
- I will not get into it now, but I want to have it designed not as a separate entity, but as a part of the whole flat.
- Is narrow and difficult to design. I would like to have some place to have small snacks of breakfast in there (optional), but for lunch and dinner I always use the table of the living room. I am open to remove the kitchen door, or installing a sliding one. It might be possible to shift the entrance to the patio to the right if this creates the opportunity to create a new space, or optimize the distribution of the kitchen. I would have to ask for permission to the community, and I cannot take it for granted.
Modifiable walls marked in red.
*Some notes*
- Another detail: I will need a discrete place for my room. No matter in the bathroom, under the bed, of somewhere in the living room.
- Should the bedroom wardrobe and dining room wardrobe keep the same style or lines, how? Should one be wardrobe and the other big shelves (sorry for the English -I don’t know the exact terms-)
- For bonus points: a solution to store, at least on bike
- I would appreciate some comments about changing/not changing the floor (putting parquet or similar).
*Furniture to maintain*
- The "Guernica" puzzle (WxH 144x68 [cm])
- The bansky graffiti (WxH 72x75 [cm])
- The sofa (220x90x90 [cm])
Style:
I like modern, but not minimalistic design.
I wouldn't go for ultra-white kind of space, again, I am not the tidiest person in the world.
I like wood. I like grey. Also I need suggestions on the materials and colours.
Furniture detail brand, model, price is optional but could be nice to know and I need a reseller in Spain, the optimal situation is to find a brand who have an online shop. (copied from another project)
I am completely open for new ideas (even crazy ones) and different styles. surprise me!

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