If I have already have a unit in my quest area and then proceed to play a quest, can I move that unit onto the quest without the use of another card ? If not, would a card like the empire's Forced March allow me to move the unit in the quest area onto the quest card (or does it specifically have to be a different zone?)  Forced March - Play during your turn.  Action: Move one target unit from its zone to another zone controlled by the same player.  

I would say yes on forced march because you are playing the card to the zone.  Quests have to have a unit "played on them" to be questing.  Units in the Quest zone already have already been played and are not eligible to Quest the way the rules for Quests read.

I'm not so sure, the second paragraph on page 11 under "Sending a Unit on a Quest" states:

"To send a unit on a quest, a player plays the unit on top of the quest card when he plays that unit from his
hand."

So Forced March may not work in that context.

And moving a card isn't playing a card.  If it were, all kinds of effects would be firing off from moving.

It pretty much has to come from your hand.

Unfortunately there is currently no way to send a unit that is already in play on a quest.  The closest possible way would be to somehow return a unit to your hand and then play it on the quest.  Forced march wouldn't work for the reasons mentioned above.  Moving a unit from one zone to another is not the same as playing a unit to that zone.

Some effects do kick in by moving, such as The Greatswords (Forced: After a unit enters this zone, The Greatswords gains l until the end of the turn), but "questing" can only occur from hand, it appears.

Okay, only from the hand, thanks for the replies.