I just met a paladin in the sewers while on a mission from the priests of Helm to clear out the Eyeless cult and also to rescue some actor and his lousy gem. I am playing a multiplayer game so I can use my own characters so I told him I didnt have room for him in my party. Will this ruin my chances at the paladin keep class specific quest? (Are the Radient Heart Paladins even it?)

Maestro

No it shouldn't be a problem (I'm going through it now).
The Radiant Heart Paladins can give you a stronghold if your main character
is a Paladin. It will kick off at completion of Windspear Hills quests.

Thats weird. I finished the Windspear Hills quest long ago, but I never even saw any Paladins (other than the ones you accidentally kill at the very beginning).