Helping others to complete quests is something that players are
encouraged to do (as allowing people to group and roleplay together
are two of the main aims of this mud), but this should be restricted
in some ways.
When none of the players have completed the quest, they may fight and
think together. What is not fair to the players and to the builders is
one player guiding a character through a quest because the player has
already completed the quest. Players can help others for the fights
and the parts of the quests where a group is needed, but they should
let others solve the riddles, find the items or the persons they need
to find themselves.
Using information from quests already completed is poor form: ICly,
most quests wouldn't be re-doable. They are in order to allow more
than one player to complete them.