Yes, some of us still use carto tanks! A "Hot Swap" is changing the carto in a tank without pouring out the liquid. Quite useful if the carto burns out and all you have left of a yummy juice is in the tank..
Good idea! I'll have to remember this trick. For me though, I currently use a Sub Tank Mini and I just remove my tip, unscrew the base, and stand the tank on end. The center tube,or chimney, keeps the fluid contained.