I'll try to answer some of them. My answers may not be accurate if Chops policy has changed over the last year and a half but this is how it was when I signed up.
1. How much space do I get overall?
There currently is no limit but that could change. Chops in the past has indicated that he will not restrict space unless he sees a site getting out of hand. In that event he has typically stated that his first request would be to verify if there are old files that can be deleted.
2. Is there a maximum file size that can be uploaded?
This I'm not sure about but I don't believe so.
3. Is there a bandwidth limitation on the downloads?
I'm pretty sure the bandwidth is the same for all. I do know that Chops has a specific file server now but I'm not sure if it has bandwidth limitations that are different that then web servers.
4. Is there a "number of uploads/downloads" per day limitation?
I've not run into a cap on this yet and I don't believe there is one.
**Note I don't work for DKP Systems so my answers may not be accurate. I've just been around a while.