Greetings onesmarmymama welcome to the forum.
Your two questions are quite closely related.
In either case, One has two choices to install switches or outlets. From the top, or from the bottom.
You have to either drill down into the wall space from the top, or from under, up into the space. Cut the hole for the box, run the wire and then connect it up.
I had thought to correct you, when you said "Fuse Box", but, hearing you say "one" outlet per room, you may have said that correctly. Do you have the threaded (screw in) type Fuses ? Anyway, the popular term for that is "Breaker Box".
So, lots of work there, crawling around in some tight places, a few hundred feet of wire probably, and a good possibility of replacing your Box with a newer "Breaker" type, or as least adding circuits to the existing box.
A fair sized job but difficult, I suppose, if you're not used to doing that kind of work.
Have a good Day !
S.W.