All your party members must be fully promoted in their current professions in order to be dual-classed to another profession. The reason, of course, is that your character will be fully promoted in the dualed class automatically.Some caution is required here. Make sure you maximize all of the skills available to your character BEFORE you dual him/her becuse if any skill is not available to your character in the new class it cannot be developed any further.
An example would be dual-classing an Arch Mage to Master Archer, if the elemental and mirrored path magic skills have not been grandmastered by the Arch-Mage, you can only develop them as far as a Master Archer can go - Master, I think. But, if you have maximized them as an Arch-Mage, then your Master Archer can use all the spells available to him at the GM level! This rule applies to ALL skills.
As far as the two scrols in Harmondale are concerned, one is lying in the road and the other is given to you when you talk to the Angel in the castle to get the quest. (Scrolls 1 and 2, IIRC). Scrolls 3,4,5, and 6 are in Erathia, Tularian Forest, Upper Tatalia, and Barrow Downs (not necessarily in that order), at or near map coordinates 0,0.
Hope this helps ya 
