broketooth,you can leave them full length or cut them to make them more stiff.Tuning the arrow to the bow (see bowmaker.net on tuning)is a matter of getting the right spine for that particular bow.That is achieved by choosing the correct spine group to get you in the ball park,then tweeking length and point weight till the arrows fly true.
Front end weight increase weakens the dynamic spine.Weight on the rear end stiffens it.Cap wraps cause no problems,you just tune with them on.Mine weigh about 12 grs.Painted crown dip would be similar.
Making your side plate thicker,also stiffens the dynamic spine.Reducing thickness weakens it.
This may all sound very complicated but it doesn't have to be.The easiest weigh for me to tune,is to pick the right spine group arrow.You can get help with that here.Then I keep a variety of field point weights on hand from 100 to 300 grs.You could cover it with 100-200 grs.Shoot 3 bareshaft and 3 fletched.Just keep changing field point weights till the bare shaft and fletched group together.You will see the difference in arrow flight when you get the right weight.
Just don't get too set on a specific weight point at first,though you can get suggestions on spine group for a certain weight.Your bow will determine what it likes.
The tuning info on bowmaker will guide you through it.
The aluminum footing is for protecting and reinforcing the shaft from frontal impacts on hard stuff.I shot a steel pipe with one,dead center,with no damage.A small one in front of the nock is a good idea too.Carbons can still break if they side slap something hard but I have yet to have one do that.I have side slapped a lot of hard stuff with Gold Tips and have yet to break one in 3 years.I did shoot an antelope through both shoulders and he snapped it running.
With the aluminum footings,the carbons have been the toughest arrows I have shot,including wood,aluminum and fiberglass.The exception might be hickory.