Your timings all look pretty good to me.
4 hour connection at Dublin is ample, immigration and security are normally good at Dublin, you will be changing from T2 to T1 but thats an easy walk.
Bear in mind once you preclear at Dublin, there is very little after preclearance other than the gates and a coffee shop, no lounges etc.
As Madfish said the guides are full of comprehensive and well put together information which will answer all your queries