Question 1: Is it worth buying the new 2 colored type, is there a noticable difference in noise?
Like DK said, the new ones are softer and wear the fletchings less than the older one did.
Question 2: I was in a sporting goods store today and the clerk told me that lots of people are actually buying the larger aluminum style to shoot carbons because it is quieter. This was not a true archery shop so I am not sure how experienced this guy was.
They use the same bristles in all of the bisquits. So I can't really see any differance in noise with an aluminum bisquit with carbon arrows. The finish on the shaft itself can have a signifigant effect on noise though.
Question 3: If using the larger aluminum style with a carbon would the extra play on sides and top have much of an efect on arrow flight/consistency?
Yes it can have a signifigant effect on consistancy or your arrow flight. Assuming it would be possible with out blowing something up think about shooting a 30 caliber bullet down a .375 bore. The arrow, just like the bullet, would rattle all the way through the bisquit until it left the bow. You need a relatively tight fit on the arrow shaft to get the best performance from the bisquit.