Dear Terence,
Regarding your first question, the structural pretwist of the blade in FAST leads to coupling between the edgewise and flapwise motions. Please see the forum topic found here for more information: Coupled blade modes in FAST (particularly, the Dec 13, 2010 post).
Regarding your second question, what aerodynamic options have you enabled when CompAero = True? That is, does StallMod = STEADY or BEDDOES; does InfModel = EQUIL or DYNIN?
Best regards,