Complete novice myself when it comes to arrows, but I might be able to give a little advice from my own ventures in this.
1- never used the dowels, although I have used bamboo garden canes you can get in loads of stores, worked well although they need a bit of work to get straight/smooth, the nodes can be a pain, and also be careful when you file/sand as they contain silicon, which isn't a good thing to breath in.
2- i haven't used one, and I think my fletch went on alright, like RBLusthaus said though, I can imagine it can only be a good thing to use a jig, a little tip in terms of what I found works. Grasp the arrow shaft between you knees and you have an easier job putting it on.
3- no idea as I said, newbie as well