I have the original Zumba DVDs. You don't need a lot of room to do it, so you can definitely do it at home if you have a little strip of space in front of your lounge. It's a good workout. If you can figure out a way to get it from your computer to your tv (or just do it in front of your computer), youtube has about five-hundred-and-fifty-gazillion zumba dances you can follow along with.
As for helping lose weight, it helped me (but I was doing a bunch of other stuff). It certainly didn't hurt! Also, depending on your weight/age and all that jazz, you can burn about 600-700 calories an hour if you're putting everything you've got into it.