To be the best ele I can be...
You can play with whatever build suits your playstyle.
1. Personally I don’t expect anything (when I’m not playing my Elementalist). But if I were to say what I’d prefer… what I like most about groups are three things: Fury, Might and Heals.
So you can play the Water 30 Air 10 for Zephyr’s (kinda nerfed though), or you can play a S/D for insane Might boons, etc…
As long as you don’t die for stupid stuff and provide help to your group with damage, heals and ressurrects, I think you’re fine (most groups don’t care about min-maxing).
2. Can’t say as I’m inexperienced, but I’d say highly viable… I see more Warriors, Guardians and Thieves complaining that they must play ranged for high fractals in fear of getting one shotted or because the damage is too high, and being far you can see the animations/large attacks coming better.
3. D/D is very viable (and fun). The damage seems a bit lackluster in my opinion, but you play sorta like a melee. It’s kinda bad to go in full Berserk Gear since you won’t have the Defense or the Healing Power to keep you up, but it’s a very solid with decent stats.
For dungeons though I’d go S/D for boons, burst, and Staff for pretty much everything.
4. My opinion is to avoid the all-stat gear.
Depending on your weapon, you’ll want to focus on some specific stats and try to get the best of it.
For example, with D/D I use Power/Toughness/Vitality gear (sometimes I mix with Berserk depending on what I’m doing) so I don’t get one shotted since I’m pretty close to mobs.
When I’m playing Staff or S/D, Berserk all the way if I’m pretty familiar with the content, or I mix some PVT pieces to get a decent health/defense depending on the content.
However since Elementalists are versatile by nature, these all-stats could be good if you don’t mind having some “all-around” stats.
Condition Damage is good when playing D/D or S/D for example, but kinda sucks for Staff imo. Healing Power and Toughness is great but it’s even more required when playing D/D than anything else. Precision is good but I don’t focus too much on it when I’m playing D/D since I get near permanent Fury, so I trade some of the critical chance for survival stats for example.
If you’re not sure where to start though, I recommend playing Staff and S/D with Berserk, Knight and Soldier gear.
Then you can work your way gearing more towards offense/defense depending on what playstyle you enjoy more, and then get your ascended stuff accordingly.