Re: 16inch barrel VS 22inch barrel
If it's just a bench gun then it seriously is JUST user preference. The velocity won't matter because it's short range. Maneuverability doesn't matter because it won't be off the bench correct? Same goes for weight. I don't see a reason to go either way for the purposes you listed. I personally like my rifles with short barrels but that's just my own personal preference and either way you look at it, both lengths are still reletively short compared to typical standard and magnum caliber guns.
I have a 21" 22lr and love it, but I want to pound small game too and it's no fun to shoot offhand with so I'll probably be trading it in for something more usefull to my personal purposes.