At this age you should just ask for favorite colors, and then you pick the complimentary covers. Real privacy demand won't happen until about 11 - 13, so right now just concentrate on making it beautiful. If it is pretty and functional, they will love it! Buy furniture pairs so when you do split them up they each have basics. Advice about dividing the room generally is good, but you don't want big sister declaring any territory! There is a crown detail you can do over a bed that includes curtains down on either side - can provide privacy when you sit up in your own bed - consider this as they get a little older and won't pull it down while hijinxing. If it is beautiful and the textiles are in a color they love (or two colors that work together, like pink and lavender on a spring green or taupe wall &/or turquoise and spring green on a buttercream yellow wall ) - then they will see that they can also be different people who are harmonious together. At 7, she is old enough to pick a great color, but don't ask the 5 year old - her taste is changing daily - just surprise her with something all her own that works with sister's pick. I like the look when people select soft goods that match except for color and find one great print accent pillow that ties colors together for both beds. Stay with neutrals on furniture - you can paint out different stuff so it is tied together with pale gray paint. Think mostly about function - Add shelves and cubbies that hold baskets for stuff - stuff changes but they always have it. If you have room, give them each a desk as they approach 5th grade.

For the fireplace inserts go ahead and do the green order a second set of panels that you store that are more neutral. In 10 years or five years you may not like the green anymore. It's possible you won't have access to different colored panels at that time. As for the color I like the ideas of going into those silvers it would coordinate very well with your blue couch and it will pull the blues out of the curtain panels. For the wall coloring use the warm golden color in the drape. There is one piece of the flower that has this color and it will balance the weight of a dark couch. If your room is small don't go too dark in this color. You could use it on the main wall and pick two shades lighter on the other three walls.

I think the roof might be a bit too dark for the brick colour. The bricks and the window joinery will blend in fine. What did you decide to do?

Personally I think the curtain colour is fine, but your header tape needs attention and for me I'd have them taken up so they hang to the floor rather than on the floor. If your hubby is handy maybe get him to make u a box over the curtain header & stain/paint it to match your furniture. Or put up a pole in matching wood.