No you dont need any helical using field points helical is sometimes needed to add more drag to arrows with fixed blade Broad heads to keep the head from steering the arrow.

What is the difference between 1 deg offset and 6 deg offset?

5 degrees

would I have to buy just the jig or do I have to buy the dial o fletch, the clamps and the nock receiver?

the Dial-O-Fletch has everything you need to refletch your arrows including instructions on how to use it.