1: No. Infusion only prevents the Mursaat monsters from killing you in a matter of seconds but doesn't change the AL of the mask. It is always 0AL I'm sure.
2: CC bows are worth what people are willing to pay for them. Can't be reproduced anymore and will only become rarer. Personally, i'd disagree that they were worth anywhere near 75k.
Infuse only serves as defence against Mursaat's Spectral Agony. Other than that, Infusing has no effect at all.
Candy Cane weapons aren't worth much nothing, other than they look neat, and aren't available anymore, so people are trying to sell them as novelty items for high prices, I suppose.
Candy Cane weapons and off-hands are pretty handy when you're starting a new character. I like the bow because it's 15 dmg always and, as all CC items, doesn't have any requirements. That said, I'd never pay 75k for one but I'd pay 1K for the name of the person that's buying them for that LOL.
1). Dragon masks are for show in cities only. If you wear one in combat good luck.
2) Candy Cane bows are very rare and the 15-15 damage is nice for when you dont have any skill with a bow but need a ranged weapon. 75k! I bet they never got it, but there are fools out there who are very easily seperated from thier money.