Vueling usually opens baggage check-in 2 hours before travel, as you indicate. It's not BA's baggage check, so I can't see you being able to check in bags before then unless there is another earlier Vueling flight and the agent is prepared to do it for you.

Going via MAD means 2 changes, and going from presumably T2 to T5. T2 to T3 is a bit easier since you can just walk to it, bearing in mind you will presumably have to go via landside due to the ticketing and checked baggage. If HBO it would be easier all round.