Also check USA Football's website for their officiating resources. I'm a member, so I'm not sure what is availble to non-members. It's good stuff, but not at all like being on the field. Pay attention, listen, ask questions (which you obviously are), and it will all come to you. You should have it all down pat in about 30 or 40 years!!!!
In other words, learn now, but don't stop learning.