Cast on channelling / Volley / Snipe or Explosive Shot

Hello,

I started leveling a ranger with a build concept in mind, but the more I play, the more I fear this concept wont work. First, here is the concept :

- Deadeye ascendancy for the frenzy charges powers.
- Using "Cast while channeling" to trigger sniper mark and volley
- Use snipe early game, then explosive shot late game once available

Here are my fears and questions :

- Using volley with explosive shot, will the extra arrows count as being fully changed if I release the skill after fully charged ?

- Using Cast while channelling with Volley, will it work again and again in quick succession if volley has a cooldown after being used ?

- How long does it take to fully charge explosive shot and will it be enough to gather the necessary energy required to both volley and sniper's mark within "cast while channeling" meta gem ?

Unfortunately, I'm fairly certain cast while channeling does not exist in PoE 2.