Memory rMBP

I just got a 13" rMBP and I'm curious if my memory usage is normal.

8 gbs of RAM

Wired: 1.60 gigs

Kernel_task: 580 mb

Active without me doing anything: 750-800 mb

I'm no where near maxing out, its just annoying me that I'm losing well over 2 gigs before I even do anything and I really only have 5.5 to use at my leisure.

Is the OS just a data hog or is there something I can do?

Also, I deleted some files and my hard drive capacity keeps fluctuating by 3 gigs and 'Spotlight Indexing' is coming and going.