It's nice to see some movement here

This coin has a nice concept, I also like the scientific background.
I think a rating system and search function would be beyond the scope of Datacoin and is better left implemented by sites that would link to DTC files or by a derivative wallet. However, the core wallet should definitely implement user friendly uploads and downloads via txid or other identifiers.
I guess voting and comments could be submitted to the blockchain, they just need to refer to the original torrent via an id (the hash of the magnet link for example).
I think the HTTP servers should parse the data from the blockchain and store it in a database, this would also allow searching, just like collecting the votes for one torrent without scanning the whole blockchain.