Large Objects

I need to do some investigation into the way Postgres handles large
objects for a major project involving large objects. My questions are:
* Can large objects be stored within a field value or must they be
referenced by OID?
* Are large objects backed up in the normal way or does special
action have to be taken?
* If the objects are restored or migrated will they retain their OID?
* If not, is there another means of referencing them that would be
persistent through migrations?
* Is it practical/desirable to store files MIME-Encoded inside a
text field?
* The obvious advantages:
* definitely portable across migrations and backups
* based on universal technology
* easy to code
* easy to reference and version-control
* The obvious disadvantages:
* slow, Slow, SLOW
* significant increase in per-file storage requirements

Any help would be greatly appreciated. Hope I'm posting to the right
list.

Dan