Re: How much of a risk did Hanlon take to commit his crime?
Well, Tommy Brown jumped out of a plane! Kay Freestone's was a risky operation, plus there were only so many people known to be in the building. There's the risk in the murder itself, but then the risks to get away with it, e.g. the dissolving suture was a great strategy until Columbo was onto it, with Mayfield then engaging in all kinds of risks that were more contorted and as bad/ worse than the original attempt.
You do raise some great points. Hanlon probably looked more like a Ding-a-Ling ice cream man than most of other drivers. We saw his sinister side, but one can imagine him smiling and waving at the gate.
Everyone learns that dealing with Columbo turns out to be biggest unknown risk. In this light, maybe it was Halperin who took the biggest risk of all.