1: A beat-up raincoat.
2: An aging Peugot.
3: A cigar (the cheap kind).
4: Follows a suspect around, irritating them until they slip up.
5: No apparent first name (actually, he does have one: Lt.)
6: A never-seen wife.
To call someone "Columbo" or "a Columbo" can either be taken as a compliment or a threat.
A 'columbo' is named for a the TV show detetective by the same name who was known for his phrase at the supposed end of his questions/investigation "oh yeah, one more thing" - and USUALLY that 'one more thing' is the 'kicker' as it were.
That airbook setup had more columbos than I could count!