Hello and welcome to the Cafe!
I think it is very doable when you divide it into multiple mospline objects and choose a right formula, you can check the attached file for a rough example.
TreeSetup.c4d.zip
You can do it using Pose morph as you make 2 objects your original object and a copy of your donut with a rectangular hole (you must use the same points count, so just modify your original object).
You can find many videos on this, on of them is by GreyScaleGorilla.
No, it is not. It contains a lot of triangles which can cause problems if your surface gets deformed.
Try to change them into quad so it becomes a nicer mesh.
You mean rolling effect as in a red carpet rolling or something like that?
if so you just use the bend deformer while rotating it 2-3 degrees so it is not totally on the axis that you want, this should help getting the spiral look.