Jade-
I'll try to answer your questions. I have a Juki 98Q and a GMQ frame. I have the sure stitch regulator as well. The difference is this- the cruise control is a just a speed control- if that is what you have, you still have to move the machine at a constant speed to get even stitches. The Sure Stitch is a stitch regulator, which means no matter how fast or slow you go, your stitches remain regular and even.
Lots of people have said that you don't really need the stitch regulator, but I really like having mine. It means I can try out new things at a speed I'm comfortable with and still get even stitches, so it was worth the money for me.
I didn't buy the pantograph thing, because I prefer free motion, so I can't answer that question.
I will say that the stitch regulator is tricky at first, and also that Grace company has the best customer service ever- if you run into trouble, CALL them first!