>>1373356 (OP)
If you have a .torrent file, then it already contains the information about its contents - a list of files and their sizes.
A magnet link doesn't, because it's just a description (hash) of a .torrent.
But also, paste the hash into btdig (or some other indexer / archiver of magnets), and if its crawlers encountered this hash in the wild, then the information about its contents is saved there. For example:
https://btdig.com/0f2a31835cd41c8e11d41209ad46e6ba45a0fc1f/
Peer list is not a part of the info about the torrent as such, first and foremost because it's dynamic information that changes every minute. There's a random number of people seeding or downloading this torrent at any given time. Some of them are discoverable be you by announces to the trackers or to DHT. Some others might not be (different peer swarms, connectivity issues, etc).