Welcome back to the hobby!!! I took a few years off too, but have been back at it a few years.
I have all the answers you're looking for, but I'm a Red Sox fan, so I don't want to help you, Yankee fan!!!
Hahahhahaha, I'm just playing. I'm a die-hard Boston boy, who likes to have fun.
In all seriousness, I haven't ventured into boas yet, so I'll let others help you there.
I can say that, yes, a tub will work as a grow-out enclosure, though. But other than that I'll let the experienced boa keepers help you out.