Helical does mean turns to the right (called right wing helical) or to the left (left wing helical). I fletch right and left helical and see no difference. I shoot right handed. However, as mentioned above, do not mix right and left wing helical feathers on the same arrow.
If you buy a jig, be sure to match the feathers with the jig. For instance, you do not want to glue a right wing helical feather using a left wing helical clamp, and vice versa.
Fletchtite is a brand of adhesive designed to glue feathers or vanes to arrows. Fletch tape is a thin double-sided tape that can be used to attach feathers to arrows. I have tried both and prefer fletchtite, but others swear by the tape. As mentioned before, be sure to scrape all old adhesive from the arrow shafts and use a good solvent to remove all oils from the shaft. Also, once you clean the shafts, do not hold an arrow where the fletching will be attached with your bare hands. The oil on your skin can prevent good adhesion.
Keep a rag handy to wipe excess glue from your arrows and possibly finger tips. It helps to have a piece of newspaper or grocery bag at hand upon which to set the tube of adhesive while placing the jig clamp on the arrow.
The standard arrow fletch length is 5 inches. Some report getting good arrow flight with 4-inch feathers, though. It depends in part on the length, weight, and diameter of the arrow your son is shooting. I fletch with 5-inch feathers.
When you fletch arrows, you want a nice even bead of glue along the entire length of the feather. Once all three feathers are attached, place a dot of fletchtite on the leading tip of each feather and on the back tip of each feather. I find this extends the life of my fletching.
There are many videos on youtube that show the process for re-fleching arrows.
Your son is lucky to have a Mom that would make this level of effort for him. Never feel like you are asking too many questions. If you don't understand the answers you get or don't get answers to the questions you ask, keep asking!