Expunging felonies?

O.K., a few questions (this is just a theoretical question so I'm not looking for info about a specific state or crime):
Having a felony automatically disqualifies a person from leaving the country, right?
The only way for a felon to leave the country is to have the felony expunged, right?
How difficult is it to do this?
How long does this usually take or does it just matter on the specific situation?

Having a felony record does not automatically result in a denial of passport, there by preventing you from legally leaving the country. However, depending on the charges some contries my deny an entry visa.
If you are subject to felony probation you may not leave the country(or state) and in some cases even county without permission from your probation department. The same goes for persons paroled from prison with a felony.
As far as expunging felony records, for serious felonies this requires a presidential or gubinatorial pardon. Many juristictions automatically seal records of juveniles.
For less serious felonies, upon successfull completion of sentence and probation, if you can show good cause and substantial evidence of rehabilitation you can petition the court by notice of motion to reduce the conviction to a misdemeaner.

Thanks