its an anonymizing tool like tor, but i2p supports bittorrent while tor does not. theirs also .i2p site like tor .onion sites. also i2p is peer to peer while tor is volunteer run with the tor project managing the network.
Steak and eggs, it's what astronauts use to not shit for days. your body absorbs most of the material rather than excreting it. your looking for anything "low residue".