A new station is planned for Pelletstown, this is in addition to Broombridge. Both appear on IE's map. Broombridge is likely to be rebuilt and moved back towards Liffey Junction when the Luas to Liffey Junction is built, Liffey Junction is the curve about 200m on the Drumcondra side of Broombridge.
The new stations proposed on the Maynooth line are
Pelletstown between Ashtown and Broombridge, previously known as Ashington
Phoenix Park between Ashtown and Castleknock, previously known as River Rd
Porterstown between Coolmine and Clonsilla
Broombridge is the pits, the local vandals tear down or burn out anything new is put in. The ticket office was burned out at least twice. Add in the failed attempt to derail a train and lets not forget the urban legend about the bouquet of flowers, which in fact is true
If you are a Maynooth line user and wish to go to the airport via Metro we suggest you make a submission to the RPA
http://www.rpa.ie/metro/have_your_say specifying your desire for a interchange at either Glasnevin Junction or Drumcondra. I met and spoke the to the RPA yesterday about this and they want such but appear to need to force the budget situation through public support, they didn't say that its my read
On the overall Maynooth line, from experience with IE, lighting, signage etc they will fix if they are put on the spot, services and timetables they stubbornly refused to make any moves. If you want security at the car park then you will have to pay