I've got a .454 Alaskan also and shoot primarily handloads.
Cant help with #1 without more info or pics.
As for #2, you really gotta use a hefty roll crimp to keep the bullets from jumping under recoil. Depending on the loads you're using and how you hold the thing when you shoot it, even with a proper crimp you may still see a little forward movement in the bullets. The gun is light enough that it accelerates pretty violently which only makes the problem worse, especially when you're using really heavy bullets like the 360gr. The heaviest I've shot out of mine are 300's and I've had good luck keeping the bullets in place with some max loads.
Experiment with havier crimps. If that doesnt work, you may have to either decrease your powder charge, change powders, or go with a lighter bullet.