Warlocks: If anything, I think warlocks would find more utility in being able to strip buffs (dispel) or bypass spell damage reduction to some capacity. As it stands now, Gust would be alright but wouldn't really do all that much except for the cheap one shot kills of gusting someone over flying areas. With control weather, you can force people to ground simply by creating gales anyways, so I don't see the point of Gust as that part is kind of already taken care of.
What I'd like to see is more spell versatility. They have Magma which is a one trick pony. Make Earthquake more damaging since it's so easily bypassed by flight. If that was done, it'd give control weather more utility than forcing people to the ground for tracking purposes. The prone affect of it could stand to either last longer or it's damage buffed. Maybe a master skill like Tremor or Magnitude that causes the damage of earthquake to raise exponentially or something.
Scouts: Camo on the beach. Camo everywhere except in cities. I don't think they need hide so much as just more versatility for camouflaging. Hiding is more of the rogue's trap and ambush would be nothing but a lesser, ranged version of backstab if you could do it from hiding. This tends to intrude on the rogue's turf a bit too much.
Bard: I like the idea for the bards. Might actually be able to reduce the output of melee a bit if you can affect their skillset like that. Might give bards a fighting chance in melee combat...Possibly. Also, shield block. Bards need shields, even if it is as simple as a buckler.
The Hellion thing reminds me of a red mage from final fantasy. Enchant weapons with hellfire so on and so forth. Seems kinda neat.
Spirit projection is pretty cool. I like the sound of it as well. Replace voodoo with that plzkthx.
Keep in mind I haven't played in a while so my thoughts are based off of some older runs of when I played Mephistir and Grenth and Syrina.