How some of the mythics works?

Hi Dungeon Quest Players! I am using a Wizard that uses Wand as MH(farming to get Eternal Fabled Staff) and Mana Shield as OH and Poison as Element. I really like the storm — wand’s special skill ---- and planning to put Discordance mythic(maybe on ring).

  1. If I put Skilled mythic will storm gain 50% damage? Because the Primary and Special switched because of Discordance.

  2. If I put Exposed mythic Pierced enemies take 50% more damage, Does storm counted as projectile?

  3. If 1 and 2 is not possible what mythic I can put on my chest?

  4. Should I put mythic on my MainHand.

I currently have 90k mana and my talents are:
Barrier (27) - Mana Shield MP consumes -40.5% MP. //Should I change to Focus for damage?
Infusion (27) - +135% of your All Resists applies to damage taken by your Mana Shield. //how about wizardy here?
Bewilder (27) - Projectiles have a +40.5% chance to Stun. //If I use Magnify will storm AoE increase?
Empower (31) - +77.5% Power, -78% Max HP. //I think I’m good with this because I’m basically uses mana for survival.

additional questions:

  1. I increase my mana for survival. Is it still good to put Sanctuary on my Amulet just in case. or just go with Empyrean? This is for PVE.

  2. So that I gain Mana should I put Serenity on my head?

  3. Discard all add HP affixes and add +Mp, Mp on hit, % Total Mp and glasscannon.

I hope you help me. Thanks in advance!