It's actually easier to buy two wands with 10% critical chance each than to get a staff with 20%. Also, while dual wielding wands it's much better to use spells (with savage sortilage) so after you got some nice wands you don't have to shop for them at every single level-up, as you're not using them as weapons anyway.
I'd never go for an evasion build though. Too defensive for minimal offensive bonus considering the additive nature of weapon skills. I'd just take Aero 2 with all party members for Uncanny Evasion, Nether Swap and Teleport. Helps with issues.
IMO with a wizard putting 2-3 points in any elemental skill is enough. Maybe 5 in one or two disciplines later, if you want to use the 3 source point skills. Otherwise the rest should go into scoundrel. But upping crit chance is also possible with gear, especially as fire runes grant INT bonuses too. So I'd max INT before going for WIT.
I guess compared to physical weapon damage wands fare even worse than staves, their damage being reduced twice with each shot by elemental resistances. Bows or two handers have a much higher damage output, and they will do full damage. As you progress in the game most enemies will have at least 20% resistance to all elements making casters weaker than physical damage dealers overall. I still like having one caster around for CC and to deal with massive physical armor foes.
