Hi there,
I hope you enjoy your trip over here. It'll probably be raining but that's just normal
If you are planning to go around in NI then get the Zone 4 iLink ticket. It's £16 per day and it's an unlimited rover ticket. It covers all train and bus travel in NI. Unlike most of the rest of the UK, the transport company Translink provide the trains, buses and coaches. It makes ticketing simple.
iLink doesn't cover the Belfast - Dublin services on either the Enterprise train or the various coaches. However, I have heard that sometimes it has been possible to get the Guards to accept iLink tickets on the Enterprise services for trips that are entirely within NI (Belfast <--> Portadown or Newry)
If you want to see depots, then there are two in Belfast, near Yorkgate and near Adelaide. They're not huge and fairly difficult to see clearly. You can at least see the Yorkgate one from the train. The one at Adelaide has big fence but you can see a bit from the bridge at that station.
Stock is, as metioned, all CAF DMUs. They're quite nice.
If you travel out Belfast to Bangor, sit facing travel directoin on the left hand side as the view is far better.
If you travel out Belfast to Larne or to Derry/Londonderry, sit on the right hand side.
If you travel down towards Portadown / Newry or Dublin it doesn't really matter.
if you get the iLink ticket you can get the train over to Derry/Londonderry and then get the Goldline coach back. You can also get any bus - this may well be helpful to get around espcially in Belfast. iLink also covers the airport buses - I know there's a stand at Belfast City airport where you can buy tcikets but I don't know about at the International Airport.
If you are after maps, there are usually some available at Belfast Great Victoria Street train and coach station.
Enjoy your trip!day is marvelous
Mr Toad