When you land into Terminal 1 you just following the signs to connecting flights. Its quite hassle free usually.
No use for AVIOS on CWL-DUB its all one class so no upgrades or anything. Would be great on the Premier service DUB-BOS though. If on the connection that has 3 hours you will also be able to have a decent amount of time in the EI GC lounge if you upgrade the DUB-BOS or you can purchase entry online/ at the lounge if you decide not to upgrade.