I am buying a blitz an was wondering if i should buy a straight or right helical

That really depends on what type of rest you are using. If you are using a drop away rest get the helical. If you are shooting a prong type rest or a whisker Biscuityou will need the straight. I use a Muzzy Zero effect rest and have a Jojan jig. I have both clamps, the straight and the helical. For my arrows I use the helical, but I fletch several buddies that have the WB or prong types and I use the straight fletch for them.

A straight clamp might can come in handy, but I mostly use helical. I mostly fletch with feathers too. If you think you'll do feathers, at least sometimes, you need to match the helical to the feather. It doesn't make sense to set up for feathers that you can't get locally, so check your archery shop and see whether it stocks left wing or right wing feathers. Then buy left helical for left wing or right helical for right wing.

For vanes, it doesn't matter. Left, right, straight. They're freakin' plastic and will twist and turn any way you want. In fact, that's a test question I use when I go to a shop I've never been to before, to see if they know their elbow from their forehead about archery. Pick up a pack of vanes and ask 'em if they're left wing or right wing. You'd be surprized at the number of archery shop doofoids I've busted with that question.

Even with vanes though, and regardless of rest type, Ivery muchprefer helical over straight offset.

I use a straight off set . its a matter of preference and the rest you will use

The straight clamp can be adjusted to put almost 4 degrees right or left helical on the vain if this helps

I use a straight clamp and then right offset as well.