Far as I know, there is no 'atoning' when you lose the VoP abilities. Once lost, it can't be regained.
True. But since in the hypothetical, the VoP was "under the influence," I'd allow an atonement to work since the decision was due to an altered state of consciousness. And that only once if the intoxication was voluntary, I might add. A god might understand a mistake made while drunk once, but never twice.
If the intoxication was invloluntary, I'd be even more lenient.
As for a divine focus, where does it say you can't have a simple, mundane divine focus?
By a RAW interpretation of the Vow, a divine focus (DF) is not listed among the items a VoP PC may carry.
Some (including, apparently, someone who answered a FAQ) have interpreted the fact that a spell component pouch does not include a DF (or any other foci or more expensive components) to mean that a VoP PC cannot carry one of those either. I follow the approach that a DF is not in a standard spell component pouch (as listed in the PHB) because is something that needs to be aquired seperately since:
1) Even a wooden Divine Focus costs 20% of the value of a spell component pouch, so its extremely unlikely a merchant would just "throw one in" for free. That rationale goes for any component ≥ 1gp in value.
2) The most likely source of a Divine Focus is going to be the temples and clergy of the faith, not a standard merchant.
3) Divine Foci differ from faith to faith, so there's no way a merchant would include ALL of them in a pouch or would even have all of them in stock. Some would even be outlawed depending on politics or alignment- and note that good faiths would NOT be immune from this. Consider the RW conflict between Islam and the other "Religions of the Book" (Judaism & Christianity): while some Islamic countries have a high tolerance for the symbology of Judaism and Christianity, some others bar any non-Islamic symbology or religious books (even if they permit the practice of the religion, its trappings may be banned).
4) It is also perfectly possible for a PC to create a DF with the appropriate craft skills.