1) SS lines. Any SS line should work. As they usually have the same diameter outlet. The difference will be the banjo bolt. Make sure you get the right one for the MC and caliper. My guess is any sport ATV uses the same one.

2) Rotors. For a zilla, http://www.jdscustoms.com/product-category/atv/suzuki/lt500/brake-components-lt500/

3) Don't know of any direct replacement but the Z400 front swap is great. Also gives you more wheel options too. This is not cheap at first though. If you do this, yfz450 calipers are great and dual piston. This is a major upgrade for banshees.

4) Master cylinder. Any front MC should work, as long as it bolts to 7/8" bar. I would suggest a newer YFZ450 like '10 as it is bigger and better than the older ones.