Hopeling

To expand upon what other posters have said, the Force Feedback proc has a chance to fire for each enemy hit, not just every time you use the power. In a power that hits several targets, the chance of it going off becomes very high.

I'm not sure I agree. Softcapping (at least ranged and melee, AoE seems harder) is easy if you have both SoA and pool Maneuvers, and is a huge survivability boost. It's been much more useful to me than would be maybe a 20% damage buff from slotting for that.
Only two Bane powers take the Achilles Heel proc, and if you put it in Surveillance, it'll break your stealth when the proc goes off.

The Valkyrie wings don't allow flight. The characters you saw may have been Peacebringers, who start the game with flight, or they may have been using the Good vs. Evil Edition jump pack.

I think you get one charge per 24 hours logged out.