What questions should I ask in regard to:
Painting over cedar shake shingles and blow in insulation
Or
Putting vinyl siding directly over shingles vs taken shingles off

I guess the question is do you want to cover your shingles with vinyl?

It will change the look. If you want the vinyl then it is great the first thing is what you want the house to look like.

Blown in insulation first does not always get into every nook and hole. Supports or cross beams stop it from getting in, and over time it will settle towards the bottom. And at least in all I have seen you have plug holes that can be hidden OK, but can normlally be seen if you look close.

Personally I don't know why you would take anything off if it is in good shape, ( using striping to even the surface. You would want most likely to use an insulation wrap if you are using vinyl.