Yes, I used real clamps because the stainless ties from DEI are absolute junk. They do not get tight. I went so far as using a screwdriver as a wedge to hold the tie and pulling on the end with everything I had and it was still loose. After the third one I tossed them.
I used all but about 6" of a 50' roll.
No. I wrapped from the collector forward as you're supposed to. I did the inside (front cylinder) header tube first starting directly in front of the collector up to the cylinder head, then I started at the slip on and wrapped forward, once I got to the collector, I slightly went past both header tubes then I came back underneath and continued to wrap the second header tube. This, in my opinion, gives a cleaner look but you could easily wrap just the header tubes then come back and cover both when wrapping the collector, you'd just have to figure a way to secure it in place.
The text above is my opinion. Feel free to ignore it. I do.