1) All that's happened is that armor looks and functionality have been split; you can now have any armor mod on any piece of armor, regardless of where you made it or what it looks like. Don't bother changing the armor you already have - if it worked before, it'll work the same now. If you craft new armor, you'll need to worry about insignias; until then, use what you already have.
(I use Blessed, because all my builds keep me enchanted. Radiant is unnecessary for an elementalist with an already high mana pool, but can be good for Mind Blast users. Prismatic is good for +AL, but only if you're willing to gimp your effectiveness.)
2) Fire is still the best overall damage-dealing element for PvE. The only mission you should consider switching for is the last one (Hell's Precipice). Partying with someone who brings Winter (the ranger spirit that turns all elemental damage into cold damage) would let you run fire even there, but you're not that lazy, are you?
3) I'm guessing you don't have anything but Prophecies (Chapter 1) skills. Something along these lines worked for me way back when. You should be fine with it still.
[skill]Mark of Rodgort[/skill][skill]Rodgort's Invocation[/skill][skill]Fireball[/skill][skill]Meteor Shower[/skill][skill]Aura of Restoration[/skill][skill]Fire Attunement[/skill][skill]Elemental Attunement[/skill][skill]Resurrection Signet[/skill]
A fire weapon will trigger Mark of TROGDOR along with dealing otherwise insignificant wand or staff damage, which will give you something to do between spells. Among DoT AoE spells, Meteor Shower causes foes to scatter the least (because they only try to get away after getting hit twice, at which point MS is already 2/3 through doing its job), and should work very well for tough-to-roll bosses (Willa the Unpleasant, I'm looking at you). Dual attunements will let you cast everything on recharge, which is kind of important for TROGDOR's Invocation. If you prefer not to wand things, Immolate is a good replacement for Mark, especially considering dual attunements will let you spam it.
If you fancy Water, or are at least considering it for Hell's Precipice, bring one big shutdown skill (Maelstrom), AoE damage spells (Ice Spikes, Deep Freeze), and something to round out your build (Blurred Vision for utility, Ice Spear/Rust/Shard Storm for more damage). Again, dual attunements will let you cast everything on recharge, though Ward Against Harm + Glyph of Lesser Energy may provide you with decent energy management and even more utility (which is pretty much what you have to go for, considering fire is the damage line in PvE). And of course, a Resurrection Signet (or Rebirth, if available) should let you recover if your henchies decide to kill themselves for no apparent reason
Welcome back
