Question 1
In our bedroom (which is unnecessarily large at about 30 square meters) we are planning to build a dressing room. We will build it in a corner of the room. In the same room, we will put up drywall over the sauna ceiling

(i.e., whitewashed pine planks) and also remove the laminate floor and lay parquet.
Now to my question; which should we do first? Can we start with the dressing room and then do the ceiling and floor afterwards?
Question 2
We are also planning to remove the windows facing our deck and install double glass doors there. The deck is slightly higher, which will mean we need to have a step up from the inside. Under the existing window today, there's a radiator, and initially, we thought we would just move it to one side. But now we are a bit keen to remove it completely and install a type of radiator that can be recessed into the floor. But we would instead have it at the current "floor level" and then enclose it with frames and parquet flooring and, of course, have air grilles. What do you think about this solution?