| I would have taken the entire thing from a step further back, where the interrogation was just a small part of a broader challenge. Whatever it was that they were trying to find out from the interrogation would probably be what I made the overall goal.
When you try to have a skill challenge for a very narrow set of circumstances, you run into a handful of problems. "Interrogate the captive" can be pretty much ruled by a single roll, and there's a chance that not everyone will want to be involved. If you instead make the challenge something like "figure out when and where the cult of Bane holds their secret meetings in the city of Tolin" it gives your players a better chance of coming up with a place where they can fit in.
Beyond that, skills shouldn't really come into play, or be counted towards "winning" the encounter if it isn't furthering the group towards their goal.
Checking to see if the cleric was hurt should only count if the cleric's health directly affected some later part in the challenge. If, for example, things were leaning towards forcing the cleric to sneak the party into an evil mass under the noses of the cult leader and his champions, then having the cleric beaten up and limping or maybe even dead might make things tough. If the plan is to kill the cleric as soon as they beat whatever information
__________________ Life's a die and then you bitch.  | 
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