The whole CCP/CWP varies from state to state.
It's pretty easy to get.
Following the rules isn't always easy. In some cases, it's actually easier for someone without a concealed carry permit to have a firearm than it is for a person with a ccp. Municipal and state properties? The permit holder can't carry. The guy with the rifle in plain sight is fine. It's silly, I know.
Again, by state, it varies. In states like Florida or Texas. Felony criminals beware. If you're comitting a felony act against someone with a CCP, you're gonna' get shot. Little or nothing will happen to the shooter. The law isn't written as such in Texas but to my knowledge, no shooter has been prosecuted.
Other states you have to be able to demonstrate that you tried to retreat and was left no other option than to fire at your attacker.