Yes you should be checked all the way through. Not sure about upgrade offers on the UK-DUB route, though it will be a short hop flight anyway. An upgrade would only be to the same size seat closer to the front.

At DUB your global entry will help get you through the US passport control line quicker.

Since you’re PE, OWS won’t help with the US CBP security line(which doesn’t matter since you have GE), but you will get access to the 51st and Geeen lounge after you get through that checkpoint.