I'm sorry that I can't help you with the baggage weight rules. But, like you, I too was concerned about a $35 fare from Dublin to Glasgow/Pickwick. The plane was relatively new and the flight was all quite standard....no need to worry there. The only worrisome experience was that they have very few agents working the check-in counter (sometimes, none) and only allow you to check-in about 30-45 minutes before flight time. They were extremely efficient once they called my flight and all went well.
Janet