1) its a chore. you have to click a lot in the same area, and often have to raise or lower chunks before it will flatten, even if its a minor delta. The easy way out is to use a stone floor, which solves the problems for homes by being thicker than the differences and evens it all out nicely. Outside the home, you either say good enough or be prepared to spend a lot of time. Note that the cultivator sometimes works better, and sometimes not.

2) your best bet if you like you home and hate repairs is to make your home monster proof and get away from it when its attacked. Monster proofed is a mix of a trench, hoe-raised walls, natural terrain, and other tricks like fires or traps can block a path. you will want at least 2 10x10 floors to fit everything the game currently has 'neatly' so that it looks even half decent. If you don't care how it looks or bury part of it in a pile, half that.

3) they work fine inside. You do need to vent it. it just needs space for the 3 ports to be accessible. Its big and heavy, you can't put it onto wood floor.

4) it will be here when you wake up. Put it down. Eventually that one awful body run wlll make you want to put it down for a few hours. Everything eventually gets old, but I am rediscovering building with the new bits and will be playing house for a while.