The -200's usually operate the SNN routes as well.
To answer your second question - yes, the scheduling of the A330-200's is reasonably consistent. They cover MAD-IAD, DUB-MCO, EI139 DUB-BOS and SNN. The -300's are reserved for DUB-JFK/ORD and the 137 to BOS. Aircraft can be changed around for operational reasons now and again of course.