ES Spellcaster, need help

I haven't played ES build to any large extent, but the other day a chase orb and a occultist vestment turned into this for me:
:O So i figured its a good time to give a ES caster a go :P

The current idea is to use fire, cast speed & lowlife (pain attunement) for damage, ES (with high regen tough Zealot's oath) and possibly AA for defense.

Im also trying to keep RF within the realm of possibility but this one seems tricky.

So the current idea looks sth like:

Gems:

Flamesurge - Spell echo - Fire pen. - Inc AoE/Faster cast
Firestorm - Cure on hit - Flammability - Ele. Prolif.
Lightning Warp - Reduced Dur. - Faster cast
CWdT - Enduring Cry - Molten shell - Summon skeletons / Decoy Totem

Auras / buffs
Clarity, Discipline, Purity of Fire, Vitality, Arctic armour (reduced mana & blood magic as appropriate)

Items:

Head:
geoffreys crest atm, will likely need sth with far more ES.

Chest:
shavronne's wrappings

Jewlery:
A pair of these should be a nice damage boost, and they also have okish resist. Does the burn on RF proc the increased cast speed?

Pyre could be an option to increase RF damage, but im not so sure abt that one, seems more for melee chars given the cold convert.

Eye of Chayula seems like a good ammy pick, or possibly Atziri's Foible if going the AA route.

EDIT: AA seems almost mandatory, at least with my current miserably low ES pool, so going with rares with mana regen & the Foible.

Weapon & shield:
Some good rare wand + Rise of the Phoenix

Gloves:
Voidbringer would add good damage, but likely have to go with some rares with nice resist & es.

Boots:
Rainbowstride or good rares.


The build:
First draft

90 tree v1

90 tree v2
arcane vision, more defense (little less damage)

So... questions!

How much ES do i need to be endgame viable?

Will RF burn proc the cast speed on Mokus?

Is there some essential part of dong a RF build that i have missed?

Does this all even sound viable at all? Im no noob at the game, but i haven't really done a ES caster before; most of my toons have been melee or bow builds