Yeah, even bundled DLCs tend to have noticably low entry counts. It's fantastic for those of us who, y'know, actually intend to play our games. :P

Of course, a few DLCs are bugged (which may explain your no entry count? Though I have seen some non-bugged ones get that as well, where their base games aren't bundled yet); They're listed as DLCs nested under other DLCs by the publisher, and thus- due to Steam not sending out DLC ownership data- SG won't allow anyone to enter for them, due to it interpreting entrants as not having required base content. So sometimes that's an annoyance.

For the ones that are listable, though, they're sure nice to bump into. :)

Well it's more like a puzzle driven race, you prepare some puzzles and create quests that can be chained each other, players must solve the puzzles to get the price, in this case the link to a GA or a link to the next puzzle, it's up to the creator.