1 Seems you must use the "Helpers lines" so your arcs by 3 pts can be anywhere ;)

call arc and don't release but click & move the mouse for draw any "helpers line" (even between the 3 clicks)
so your 3 points can be anywhere in the 3D space!



2 yes :) Select arc / Transform / Rotate as you want normal or by axe

3 yes : same 1 :)

PS "Helpers line" can be used with any functions!