RE: 10 - codes...
In 1996 I got out of the Army to go to college and to support myself I worked for a security patrol company in Charlotte, NC (Hoosier Security was the name - not because it had anything to do with the Hoosier state, but because the owner was a guy named Lynn Hoosier.)
Anyway, we did a lot of security patrols, which is basically like being a cop but with only a quarter of the pay and almost none of the responsibility.

We had our own dispatcher and we were required to use 10-codes for everything. It took me a while but I actually got pretty good at it: "410 (my unit number), 10-41, 10-8. I'll be 10-17 to C-21." (Starting tour of duty, in service, enroute to a community we patrolled that was designated C-21.) I thought it was a little silly but our ex-cop owner insisted on it. He also wanted us to use the LAPD phonetics (Adam, Baker, Charles, David, Edward, Frank, etc) but I had spent too much time in the military to use a different phonetic so I just used the military one.
Actually, the most difficult thing for me to learn was to say "10-4" instead of "roger." The military kind of beats that into you, so even after I'd been there for a year I'd typically acknowledge with "roger".