In answer to your questions:
1. Any new provider will give you NCB based solely upon the paperwork you provide.
2. The accidental damage does count as a claim and should be declared to a new potential provider. Protected NCB only really counts if you intend to stay with your current provider, that said, it is possible that as the amount is small and wasn't for personal injury or a fault accident, they may not penalise you overly much. Some online providers allow you to enter claims and still avail of the online discount.