1. Yeah, convert is mostly useless except for those rare situations where you don't have any stacks of umbral ice or astral fire, and have no mana to use to gain these stacks. But compared to most other jobs getting 1-2 skills that aren't immediately useful, this is fine.

2. I imagine the point of freeze is so that you can maintain a choke point in PvP, or delay adds from reaching a point. In current content this probably isn't too useful, but may be more important in future content. About the only change they could make to this skill without making it overpowered would be to also apply a heavy debuff to things passing through (in addition to bind) so that it has a more clear and beneficial use. Dropping the cast time down to the standard 2.x seconds would be a good idea as well.

3. This skill is useless for one simple reason... Nothing in the game seems to deal aspected damage. Resistences are virtually meaningless currently. The only thing that seems to make any difference is the generic magic defense from equipment. A better, alternate skill, would be to replace this with a skill that removes 10-20% of a single target's magic resistance.

Nothing else to contribute beyond that.