1) Nope. Defog clears obscuring field conditions (mostly flavor stuff, a smokescreen etc), Fog, Mist, Safeguard, Reflect, Light Screen, hazards and any weather affecting the field. But it doesn't remove Trick Room, Magic Room and such, since they are none of the above. Also, makes little sense flavor-wise.
2) Nope. The DAT is clear when it says "Attacks that take time to charge are charged instantaneously, preventing them from being disrupted" aka only attacks that can be disrupted by multi-hit moves are affected by Power Herb. Since Fly and Sky Drop don't work like that, they aren't affected.
IMO.