Does the paladin's other powers that "mark the target" particulary some of the higher level burst-style ones, just mark the target.. or does it count as a divine challenge mark?
Just mark, unless Divine Challenge is specifically called out. "Marked" is a standard condition, like "Combat Advantage". Fighters, Paladins, lots of monsters, and probably a few other classes can all do it to people. Divine Challenge is special and unique.
Does that mean that if a paladin uses Divine Challenge on a foe.. and then doesn't attack them or engage them that the Mark remains but the X+Cha damage goes away?
Also what if a paladin moves, attacks, and then as his last action uses Divine Challenge? Would that DC automatically go away (assuming he used it against someone he wasn't adjcaent to or attacked).