i\'m no BitTorrent expert (or even a user XD), but i would think that it would \"show up\" wherever you\'ve saved it to. it won\'t show up in START -> Programs -> Planeshift until you have installed it.
what you\'re downloading now IS the installer, wherever it be on your computer. you just need to double click it to start installing planeshift. once it\'s installed, you will be able to get on to play
as for seeding, beats me. have you tried moving your plants to sun? ; D