If you want to use the trash can sized containers and worry about food-grade, just buy some food grade liners. They are easily found at restaurant supply stores (onsite and online), and clean up is a SNAP---remove liner, quick wash/sanitizing of container and you are done. (and if you ever work with fresh elderberries, the liner attracts the famous green goo). I have two rectangular lugs, and I cannot recall the volume off the top of my head but I know they easily hold 55# of grapes plus 10 gallons of liquid.
I would recommend having at least 1 three gallon carboy in your inventory, it comes in handy because some kits are only three gallons, plus you never know when you will need it for your own recipes..when you think you will have a six gallon yield but end up with nine, etc. And do not forget to have an assortment of smaller glass bottles (1 gallon, 1.5 liter, etc)--they work well for the overage that many of us create to provide a "topping up" wine of the same batch. Also remember that if you ultimately plan on using vacuum pump, you will want glass carboys, not Better Bottles---though you can find a balance of use between the two styles of carboys.
Hope your plan comes together!!
