WaringCommercial WCV300 Vacuum Sealer, Silver

Q: Does whatever meat you are sealing need to fit inside the machine and be able to close the door? Will I be able to vacuum pack a whole rib roast?

It does need to fit inside. Whatever you're sealing needs to be less than 2 1/2", so a whole rib roast wouldn't work.

Q: How is this 2 gallons? 2 gallon bags are 14x20

The chamber volume is "2 gallons", not the size of the bags you can seal. I would say that listing it as a "2 gallon chamber measures: 11.8'X12.6"X3.19" " is a bit misleading. However, they do include the dimensions of the chamber and say it has a 11" sealing bar. Disclaimer: I don't own this vacuum sealer.