I vote for an autonumber PK and let your other 9 fields be ordinary indexes, of which you can have several.
If you have constraints involving parts of your key set, make the constraining parts a compound key that must be unique. Like, USERNAME + SUBMISSIONTIME + QUEUENAME as a compound index.
You should be aware that the more keys you have as a member of a PK, the less useful the PK gets in making things work smoothly.
Also, the concept of relational databases implies that you would use shorter keys as PKs because otherwise the data in common between parent and child would be wasteful.