1) If you couldn't download a specfic torrent, it probably doesn't have any seeder. You need seeders in order to download torrents.

2) The torrent you were downloading was probably located far away from you.

2) I'm assuming you have a router. Find out which port are you using for bittorrent (google it, you lazy ), when you have found out which port is it, then go to your router page (go to your router local host address) and add that port to make it accessible.

There could be so many different things that can cause downloading torrents so slow for you, just search for solutions via google.