Crit Blade Vortex or ED? Some questions to experienced players

I'm currently on lvl75 as u can see with a decent CI gear at this point (over 8k es buffed). There is an 899 es armour waiting in the bank for crafting so I look forward to get over 10k es with almost any setup and hope to achieve 15k es with a good shield.

Currently playing critical poison Blade Vortex and really liked the playstyle and interactions so far but have kinda met a stonewall yet on low level so I'm only farming dried lake at this point. Also have played ED occultist to lvl85 on SSF hc but ripped it stupidly :/ The transition should be very quick so I strongly consider to make transition to ED which might have more late game potential. Or is it just that ED has lower skill requirements?

Some longish questions:

1) Really enjoying Warlord's Mark getting Endurance charges mitigating phys dmg down and making immortall call great again. Also liked the playstyle being almost melee. Just achieved double curse so I'll run also enfeeble and think Heretic's Veil is one the best uniqs in the game. Will not get rid of it, ever.
I just wish it will be enough defense for me. Almost ripped at merciless lab which is a bad sign. Getting too close to bosses might be deadly even this early. This is a clear sign that I really need to change something that can avoid melee boss mechanics or will blade vortex just get more powerful with better gear so I can like facetank uber izaro with lifeleech and 10k+ ES? I have started to think that the build I'm doing now is kinda needing overtuned dps which is not where I'm going now...Power charges actually take an huge hit not taking dps routes over aggressively.

2) Is double void battery mandatory to make blade vortex to work well? I look forward to maintain Obliteration or try just one void battery to see if it can work.
I see this build is made all the way for "attack is the best defense" but I prefer more defensive strategies so I have spent points from critical dmg to less mana reserved for example. I can't see my build will survive w/o protection that shield gives.

3) When playing Blade Vortex do u just skip some map addons like beyond that can summon powerful uniq monsters. Also when mapping just skip some bosses like Torture Chamber's laser boss?
Tried beyond minibosses on dried lake (monster level 67) and they felt very dangerous even on that point. I have significantly less experience from BV compared to ED!

4) Is running slower projectile in ED really mandatory dps wise 6l since I hate to make projectiles slower? It was slow enough w/o that dmg buff gem.

Thanks a lot for reading!