tev9999:
They are variable in how the rule is enforced. Ryanair check you in with their own staff at Dublin, but use handling agents at Gatwick. I have got on with laptop and overnight bag, I have also been asked to check the bag. Bear in mind that a 737-800 with 189 seats (which you will not be used to in the USA) just does not have the overhead bin space on board for more than this, especially in winter when people put heavy coats up there as well. American put 134 seats in the same airframe.
1 hour check-in is fine at Dublin, they may not even be open 2 hours before. They cut rigorously 30 minutes before departure, but as at Dublin there are separate queues for each flight, as long as you are in the queue before this you are OK, they will rush in the last few minutes to process the queue with extra staff.
Yes, you will have to go through customs both ways, this actually takes no time at all. Ryanair do not interline baggage with anybody (even themselves) so you will need to check in again in the main area. Fortunately both FR and NW use the South terminal at Gatwick. From the USA will take you time to get through immigration as a non-European, but this just absorbs time spent waiting for the bags to be delivered. From Ireland to Britain there is no immigration check and there are special routes for such passengers signed "Arrivals from Ireland". Also when exiting the customs on your return trip take the "European arrivals" blue channel (you bags will have blue-edged baggage tags) When you come out into the terminal just find the appropriate airline check-in counter (plenty of information on where they are) and start again. On your way out, having found the FR counter, you might just want to spot the NW counter's position for the trip home.
If you have a few hours to kill at Gatwick the main catering etc area is upstairs, called "Gatwick Village". From here you can keep an eye on how long the line is for security into departures. Sometimes good, sometimes BAAAAAD!
(Edited to add the customs etc bit).
[This message has been edited by WHBM (edited Nov 30, 2003).]