It is very important if you want them to fly well, you will need a really light spined arrow it you plan on cutting them that short and yes a heavier point will help some also. Best option is leave the shafts longer. Start with a long shaft and if it is to weak cut it little by little until it flies straight.
I never worry about how much arrow shaft is out front as long as they fly well. I would start with shafts that are a little less that the draw weight of the bow and cut accordingly.
Pappy