Divinity Original Sin EE - What is the gameplay of a Dual Wielding Grenade Wizard Build?

I am trying a new build in Divinity Original Sin EE: Dual Wielding Grenade Wizard. But I do not understand his role in my party.

I found what abilities to choose in a build guide:

but not how to play it.

It does not explain some (probably basic) things:

• I am not supposed to put extra points in pyrokinetics. How is the damage of fire bombs supposed to grow to keep them viable later in the game?

• Whenever the fight starts monsters are usually too far away to reach them with a fire bomb. Should I just run forward to get in range?

• What does dual wielding imply? Wielding 2 weapons or wielding a 2h weapon? Or both?

• The build says: WIELD A DAGGER IN YOUR MAIN HAND AT ALL POINTS IN TIME. Why? And is the main hand the left one when I check inventory? How do I know if a weapon is a dagger? When it has piercing?

• Are there other bombs worth considering apart from the fire bombs I am using now?

• Should I focus on throwing bombs? Or start with it and then switch to melee as fast as possible?