Heads up (SnG form) questions..

[Tropex]

I've played quite some $5.5 NL Heads up, a few Limit heads ups etc and I thought of a some things. First of all, the bankroll management - I'm very careful with my spendings, I haven't touched SnGs with bigger buy-in than $10 (have over 100 buy-ins for those) and same goes for heads ups. How many buy-ins for such should I have before moving up assuming that i'm rather comfortable with my HU play overall. I've heard recommendations for ring but never SnG form HU.

Also another question - I play at PS and I've noticed the level of $5.5 Heads ups is pretty low, at which stakes should I expect to get to play more players with any class than total fish with no idea what they're doing ? =]