1. If he was born in UK to British parents, and was therefore British at birth, he cannot have a certificate of registration as a British citizen, so I think the answer must be no.
2. Yes, attendance at a citizenship ceremony is compulsory for people being naturalised, except for the very old or seriosuly ill. If you can't attend one, your application will be refused. The ceremony fee (£68, I think) will be refunded, but the Home Office will keep the application fee, because they will still have done the work....
