I will let you sleep then, It stands for Concealed Carry Weapon
1. Yes, 21 is the minimum age that you may aquire a concealed carry permit
2. A general rule of thumb, carry the biggest gun that you can conceal properly, and that you are comfortable with. Some states require that you have your carry firearm registered as such
3. This varries from state to state, for instance an Iowa Resident permit is valid in AK, AZ, ID, MT, SD, OK, TX, MO, TN, KY, IN, MI, VT. other states may have more or less reciprocity
4. If the firearm is unloaded and in a case, or in 2 or more pieces then you do not need any license (in Iowa at least). If you want to keep a loaded weapon in the vehicle, then you need a CCW.
I could be wrong, somebody please correct me if so
If you are looking for more info on CCW go to
www.packing.org its the best site that I've found for these types of questions