I just want to clarify that this is the slab floor you're talking about and not something you are adding to a raised foundation? If that is right then it is a cheap solution and may be fun to do. Adding a laminate wood or carpet later is possible but in the case of wood laminate could result in the big chubby extra trim around the base moulding which a floor done by a good floor guy in the original buildout won't have to add.

I think your original idea to put the TV on the wall between the sliders was correct. I don't think a TV ever belongs in front of a window. After you move the TV, put the two chairs closer together under the window with a table between them, and rotate the sofa to face the TV. You may have to angle the TV (but not the TV cabinet) toward the seating for viewing, but I think it will be a more satisfactory arrangement for you.

The blue is awesome (grey is too trendy)! The reason it stands out to you is perhaps because it's the only real colour there. Bring in the blue in a window treatment, a small appliance that sits on the counter, a pretty tray or area rug. Also, it is more appealing often if there are more than 2 colours - so right now you have a white and blue colour scheme - bring in red or orange or fushia - something from the other side of the spectrum (like you did with the yellow flowers but in a more permanent way)!

Paint your house and ceiling first. You are probably asking for trouble if you put the floors down only to paint over the top of them. If you can, remove the tiles in the kitchen and paint just behind the line of the splashback too. Once painting is done replace kitchen benchtop then splashback. I would call the bathroom its own job and do it individually, unless you only need to paint the ceiling and if a tiler doesn't need to be brought in for anything else in the house? A lot of bathrooms now are getting tiled from floor to the ceiling if this is the case, paint the ceiling first, then tile. If walls need to be painted, it wouldn't really matter if you did them first or last, though if you did it first expect to do some touch-ups. I guess if you really wanted, you could do the first coat before tiles then second after... I don't exactly like stopping and starting painting, so I would do the walls (if they needed to be done) in one hit, after its been tiled. Well that's the order in which I would do everything... Really, for what you're asking, the painting could be done at anytime, but to make life easy on yourself, I would definitely recommend doing it before the floor.