Hi I take it you are going with Aerlingus?
We did that trip last year from Edinburgh and it was great.
You pre clear as you said on the way out and it was fantastic to get off the flight in Orlando and get our bags and off to the ME. We were at our resort in 1 !/2 hours max. Remember to fill out the blue customs forms before you go through the desk, they have plenty kiosks and desks to do this and you only need one per couple/family group.
Yes just get off the flight and follow the signs for connections it will take you where you need to go. The pre clearance area is big and well sign posted. Just look for the large American Flag. We were early for our flight so the first guard told us to go back upstairs for an hour as once you go through there is not much there. One small food stand and a very very small last minute duty free which had just a couple of bottles of spirits and a limited tabbacco selection.
There were a number of security checks to go through. I think it was one when we left Glasgow, One when we got to Dublin, and one before we got on the flight. Two in Dublin on the way back as well. Seemed to be a never ending run of them But if you have all you liquids and belts/shoes off quick they don't take long to pass through.
On the way back you go through Immigration for Dublin for entry to Ireland and then again on entry to the UK at Glasgow. Both of these were very quick.