There used to be a server list for maybe two years ("multiplayer" menu item in this version), but people didn't really play the mod that often, so I eventually stopped paying for that, and now there's not. Maybe there's a Spelunky-related chat somewhere where you could look for people to play with?
As to skins, I regret to inform that the weird robot thing is about how far my art skills go. The rest of the characters are those that were already playable in the base game.