In federal parliament, what do the 2 silent people in robes sitting to the left and right side of the speaker do?

Clerk and deputy clerk.

https://www.aph.gov.au/About_Parliament/House_of_Representatives/Biographical_Dictionary/The_Clerk_of_the_House_of_Representatives

What about the people in what looks like green private school uniforms? I think they're "attendants" but can't find any mention of the weird high school looking get-ups they have to wear.