The crimp is there to hold the bullet in place during recoil. I go with the smallest about of crimp I can get away with. It just depends on how hot your loads are going to be. The ones in the pic are ok but you might get away with less. Also the harder you work the brass by putting a heavy crimp the shorter the life span of the brass not to mention it can affect accuracy in a big way.
OAL can be shorter or longer if your gun will allow it. Just remember when you shorten the OAL (push the bullet farther into the case) you raise the pressure. So again it depends on how hot your loads are. If your just starting out you shouldn't be loading to the book max. Start out a few tenths above minimum take them out and shoot them. Get to know your equipment and procedures before you start experimenting. Reloading is fun and it's very satisfying but you have to remember it's up to you to keep it safe.