There's room for a rollaway bed in the suite. Call them and ask; I'm sure they'll oblige.

From the hotel to the Aviva Stadium by taxi on a match day in rush hour is not much less than an hour at best, plus the roads around the stadium will be closed so they will have to drop you off 5-10 minutes walk away. If it were me I would get a bus into the city centre and pick up the DART train at Connolly to Lansdowne Road, which is feet from the stadium. Won't save a lot of time, but it'll be substantially cheaper especially if you have (or get) a Leap card.

Other option is to rebook at the Conrad if available.