According to " Hornady Handbook of Reloading #5" the starting load is 32.6 grs. @ 2100 f/s; Max. 44.0 grs. @ 2600 f/s of Varget. When you change any component, one should start with starting load.

Yes. The cannelure around the bullet is used for crimping.

Yes. If you don' t crimp the cannelure it is insignificant for that round, but they are important in some applications.

Yes. An unused cannelure' s position on the finished cartridge will not do any harm.

If you get a chance and haven' t already, read up on cannelures and crimping. Good luck.