Been a long time since I fletched. I have straight, left and right helical clamps. Use the same bitzenburger. Just be aware it's pretty fiddly to get them set right to use the first time. Once you got it it's set it and forget it. Clean your arrows where the vanes will be glued on.
The length of the arrow you can measure to your rest and add some to it. When you bought your bow or they made your arrows they should have given you a sheet on the receipt that listed the length of the arrow as cut, the spine, left/right helical/ what vanes etc...were used in the building of the arrows.
Straight nocks sound like those old school straight notch arrows that were mainly used for traditional archery. Modern nocks snap onto the string. They have a bunch of different brands. Your nock choice should have been listed on the build sheet for the arrows as well.
Archery talk website has a whole section on arrow making.
Always shot bonning nocks like these.
So if you get someone else to build them they should make a built sheet with type of arrow, type of vane (color of all 3 and how you want the cock feather, the off color one cock up, cock left, cock right etc..) nocks, length, insert used and if you want the vanes fletched with a certain fletch like 120, 4 at 90degrees or straight fletch etc...
If I get motivated I have a few boxes under my bed I may look and see if I have a build sheet later.