Just use Tor bundle and that’s it. The only way you can shoot yourself in foot is if you use flash uploader and that bypasses Tor (fortunately plugins are disabled in Tor bundle AFAIK).
Seeding via Tor? You need to configure Torrent client to use Tor, make sure it doesn’t leak anything (DNS lookups, publishing to DHT or tracker, some stuff on the protocol level was a problem as well). There’s nothing that comes working out of the box. Of course it’s not rocket science, it’s just a bit more work.
Hosting just via hidden service is actually worse than uploading to random locations on clearnet:
1) Still no way to do load balancing with hidden services
2) It’s usually slower anyway
3) If your server gets compromised you’re toasted, unless you use hacked servers, or buy your servers with Bitcoins or stolen CCs.
The best network for publishing that kind of leaks would be Freenet or I2P + Tahoe. But those are not nearly as popular (and secure) as Tor.