For release details, what's the difference between XBL DLC and plain DLC? Why is there no such option for other platforms, such as PlayStation? Is there a point to all these options? Should there be more options or should they be combined under one general DLC label?
I also asked this in the issues/suggestions thread because I think this needs a technical solution as well, but for now, I just want instructions. What do Direct Download and Online mean, what's their difference, and what's their relation to Steam? For example, if a game has been published (without a physical release, as is common for PC titles) on multiple download services (e.g. Steam, GOG, Origin, uPlay), what would I choose as the distribution method?
You're referring to the Distribution field in the Add/Edit Release section - honestly, I wouldn't worry too much about the details in there. This is something that was carried over for Machina from the "Pro" section, as his charting tools require understanding what is "Retail" and what is "Digital" - those drop-down options came from that part of the site.
You'll note the information isn't really displayed anywhere on the game page (other than if you come into this option, to edit) - so I would just say, unless you know for sure a game is a "Retail" distribution, I wouldn't even bother with the field (we're perfectly fine with having it left blank). If Machina needs it set to something specific, he may do so himself... :)