Hi, Im from Wexford - Great place for a hen night, you certainly wont have any trouble getting in anywhere.
Centenary stores is good but it does get overcrowded on a Saturday night, for a group thing like this i would say go to either Sinatras or Renaissance (Above Chocolate)
I would also second going to Vine (gorgeous Thai food) or Springsteens, they are in the centre of town and both are great for hens!
Whites hotel is also in the centre and might be good for accomodation, there or the Talbot Hotel.
If you need any more information let me know....