I'm not sure how you would go about keeping it warm over time. I guess you could put it on a hot plate. I have a gas stove and of course you wouldn't want to set the glass coffee maker over a flame. But, if you had an electric, flat top, that would probably be ok.
I drink my coffee cold so I love it. I make my coffee, let it cool right in the maker, and then put it in the fridge and it lasts me for about three days. The coffee makers come in different sizes. Mine holds 6 - 8oz cups. Amazon has them in different sizes and there's one listed as being for 10 cups, but I don't know if those are 8 oz cups, lol. I'm thinking that a "cup" of coffee is 6 oz... is that right?
Anyway, I love mine. I've tried other coffee makers and this is the only one I've stuck with. I've got one that was over a hundred dollars and had a built in coffee grinder, etc. Was such a pain to clean though! The chemex one is so unbelievably simple. And, you can visually see that it's clean. There's a long, wooden handled brush you can get for cleaning them. I highly recommend getting it for convenience. And, I got my chemex as a coffee shop and got the chemex filters there at the same time. But, the filters were the wrong size so they would actually fall down in the coffee maker if I weren't really careful. Turns out the filter was simply the wrong size for my maker. When I ordered more filters via Amazon, I got a better fit size and it's been smooth sailing from there.