2.09 TB combined bounty on w/cd. Not quite good for top five.
https://www.whatinterviewprep.com/ -- if invites are currently open, which I think they are. I've heard the interview is hard, but I disregard that completely. The hardest part is probably getting someone's attention on IRC. Or you can just get an invite from an existing user. I have a bunch. Do you want one? Are you responsible? Do you have good bandwidth and actually want to use the site a lot? Oh and what country are you in some of them are banned. (I do find it extremely amusing that what uses statistics-based racial profiling and no one has a problem with it. I don't, of course, but I'd expect someone to.)
Can't hurt, but no. If you do need a public tracker for anything, VPNs are advisable (and most security wonks would say here that they're advisable anyway and the best one costs like 35$ a year). Variety of subreddits with great info on this stuff. However, I don't bother at the moment, and private trackers take care of that thing for the most part. They also aren't the target of the big anti-piracy orgs -- neat AMA a while back that I can't find from someone who had worked at one, said they mostly had accounts on all the private trackers, used them to keep an eye out for scene releases and stuff that might spread to TPB etc. Really interesting. Germany's fine.