That vent hose goes in the back of the moter rite in the middle of the cases below the rear motor mount.
40:1 is what i mix mine at, what kind of oil are you running?
Kicker just needs rebuild to get it to stop ratteling, as far as it sliping past the stop it may be bent or just wore out. They are pretty cheap on here or ebay.
The bike looks good from what I can see, post some more pics of it.