Do I need to cook the ready made sauce from can like spaghetti sauce.

Use the canned sauce in a pinch, but feel free to add some onions, carrot, celery, fennel, olives, spices, or whatever you like to make it more tasty.
This works better with a tin of crushed tomato (low salt) and add a bit of tomato paste.

Nope. If it's canned it's cooked and sealed so just reheat It and mix your pasta In.