I've read the documentation on Media Cache (http://help.adobe.com/en_US/premierepro/cs/using/WSF08BCDDB-FCD7-40a2-8290-8872EE725E6B.ht ml#WSa41b87baf39dd9b0-4a7aee25125bce32690-8000) but I didn't understandt what are exactly the formats/containers that Premiere Pro creates cache for?
Also, am I remembering wrong, but was in Premiere Pro CS 5.5 and CS 6 the cache for the project was kept in the same folder as the project?
Does Premiere clean the Media Cache regularly or I have to remember to do it from time to time?
I don't think that much has changed regarding the treatment of cache files from CS5 to CS6 to CC.
Here's how I manage the cache files:
1) Set Premiere to store media cache and media cache database in a drive folder separate from your project files (use menu: Edit / Preferences / Media and then browse to where you want them - I use "X:\premiere_cache"). This way, when you back up projects you are not backing all of this stuff up too.
2) They do not clean up for themselves - go to the same panel mentioned in #1 and click the "clean" button to remove all of the files. When Premiere Pro is closed, you can manually delete all of the folders created by Premiere and you will not destroy anything that is recoverable.
The purpose of cache files is to prepare some files additional your projects and media for performance enhancing reasons.