A glass jar should be fine, as long as you leave enough at the bottom to start the next batch off. How much is enough? I would say that 'enough' is an amount that lets you take out a day's fermented food, replace it with water and dry feed, and have the whole jar be just as fermented the next...
CV is optional. I used rainwater and pellets and nothing else, and the process started well and continued well. I believe the trick is to acidify the water slightly, to favour the fermenting bacteria and yeasts. When I started out I kept the mix in separate batches underwater and drained each...