H1B departing the US

Advice needed

Hi everyone, I am in H1B status that won't expire for another year (till 9/15/09). But I don't want to stay for another year and think about leaving early. I need your advise on planning for departure.

I need up to 2 months to take care of everything. The issue is with my employer who usually takes two weeks to process last month check and 2 months if i were to cash out retirement accounts.

Questions:
1. How soon must I leave the US after ending my employment?

2. How can I obtain extra 2 months to settle everything here in the US?

3. Should i leave all my retirement fund here in the US if i were to retire in another country (say Canada) ?

Any advice you may have will be appreciated. Thank you