I like what I see, overall. I'd love a chance to playtest one of them, too.
As for the Hydromancer, I see it as having aspects of all the other versions, and would overall be the most balanced, role-wise, or potentially leaning more toward battlefield control. I think after fire, cold is one of the most commonly-resisted element types, so obviously that would need to be addressed. As for save-or-die/suck effects, drowning by filling a breathing creature's lungs with water seems to be relatively equivalent to the aeromancer's suffocation, though if you go with the obvious ice/cold effects there's a good argument for slowing/freezing/shattering. Acids and poisons are also associated with water, so there are good cases for those as well.
Honestly, a hydromancer could be fairly diverse in powers, and relegating it only to water and ice attacks seems limiting. There's enough material available to simple separate out cold attacks altogether and make a cryomancer, leaving the hydromancer to thrive on its own merits.