Hello folks: I have never been to Ireland and know nothing about DUB. All I know is that DUB offers pre-clearance for US-bound flights. I am considering flying EI from the US to LIS via DUB. The fare in J class looks good, but am choosing between a 6-hour, day time layover at DUB and an overnight (plus half day) layover.

I know that for the second option, I can spend some time downtown but have to go through security checks again on the second day.
Does DUB offer express lanes for immigration and/or security checks for J passengers?
How nice are the EL lounges for US- and Schengen- bound flights? Are there time limits to use these lounges?

I am a newbie and therefore would appreciate all advice I can get. Thank you in advance.