Schwabee
There should not be a problem with your die touching the jaws of the shellholder. I guess I should ask if you're using the auto-universal jaws on the Forster or the regular type shellholders. If your dies are not fitting down into the recessed area of the universal jaws, then it would be OK to bevel the outside edge of the die. I would not take any off the bottom end of the die unless I absolutely had to, but it can be done and I have done myself with out any problem. You need to make sure you grind the die level and as smooth as you can, but I don't think you will need to do that unless you have a very small(short) chamber.
You really don't need any fancy tools to measure your chamber, just a candle. Simply smut your sized case and chamber it to see where it(the smut) is wiped off. By varying the sized length and watching the smut removal, you can measure exactly where to set your die so the case fits your chamber. You can check the seating length of bullets the same way. Smut the bullet, chamber it, look to see if the smut has been wiped off and adjust until you get the OAL just right, of course you have to deal with magazine length too.
I should add that the auto jaws are not different than the other type shell holders as far as contact, they are the same thickness as the regular shell holders are. Treat them the same as far as touching...slight or tight.
Jimmy K