You don't need to get a whole new helmet as you can get just the outer shell on it's own and reuse your existing headband, adf, front cover etc.
If you do want a new one have a look in the for sale section
No, because the flip up portion of the helmet rides over the area where the peg is.Also, do you even need that peg?
I know it allows for adjustment and positioning of the headband but once you have got it in the place you want it could you not just drill a hole through the shell where the peg was and use a small nut bolt/rivit/cable tie to hold the headband adjuster there?