"I had a curry and rice for dinner."
Translation:Ges i gyri a reis i ginio.
Traditionally there used to be a "Mi" before this sentence (it doesn't mean anything other than that it infers that the following sentence will be positive). In modern welsh this is often dropped (but not always) and so you are left with "Ges i", but because the thing that actually caused a mutation is now gone many people say it un-mutated and therefore both forms are considered correct.
Yes, although the mi is often dropped (especially in the South) most people keep the mutation. In Northern dialects the mi usually remains and so does the mutation.