Attaching an Archon to a unit of Grotesques

Good day,
I have a game coming up soon, and have a question regarding an Archon in a unit of Grotesques.
I know I can attach an IC to a unit, and have read all the IC rules in the rulebook. However, here's what I'm curious about:

I want to deploy the Grotesques to zoom up close to the enemies to get into CC on turn 2. For this I'd need to have them embarked and deployed at the start of turn 1. So:
1) Can an Archon be deployed with the Grotesques in the raider?
2) For formation purposes, does the Archon count as an HQ unit even if he starts as part of the Grotesque unit? As in, does he still fill the HQ slot while embedded in the unit of Grots?

Thanks!

Yes to both questions

Sounds good. I was mainly wondering because the Codex states an Archon may take a Venom as a dedicated transport, but in this case he'd be taking a Raider, right?

No, he'd be embarked on the Grotesque's Dedicated Transport (or one from the Fast Attack slot). He could still take a Venom and simply not be in it.

The Grotesques can take their own DT raider, and the Archon can join them aboard.