Applying 4 to 6 weeks in advance is a good idea but their are options.  From the US passport site:

ROUTINE SERVICE
As of ( Saturday February 12, 2011  ), we are processing routine applications in approximately 4-6 weeks from the time of application.

EXPEDITED SERVICE*
As of ( Saturday February 12, 2011  ), we are processing requests for expedited service, that include overnight delivery to and from the Passport Agency, about 2-3 weeks door-to-door*.

I think the Expedited service adds about $75.  There are other private for profit services that promise 24 hour delivery.  Not sure but as I recall maybe $100 fee.

And I to have heard reports of a recent dui being reason to not admit you to Canada.  No quick answer or service for that, though I'm not sure a murder conviction would keep you out with the right lawyer and enough money.