So I'm focusing on stealth this time around, but I was wondering what kind of armor I should use [light or heavy]. Should I just use light, or would it be better to use heavy armor and level up a lot so it acts just like light armor?

Light armor is better than heavy in every respect except for the anti-stagger perk. With decent smithing, you can easily reach the 567 armor rating cap with any light armor.

Definately light armor for a stealth character.
My warrior is even useing light armor.

light armor is best cuz it makes less noise than heavy armor.

iv bin using heavy since i started and im like a silent tank almost never bin caught it all depends on how you do it if you dump a lot of points into you sneak and heavy you should be fine work great for me
and as far as i can tell its better due to the fact that once your heavy is maxed out your near invincible if you do get caught

i could be wrong but....doesn't light armor have the muffle perk?