Given that myself and my siblings are out of the primary system in Ardee since the early 90's, I can only vouch until then. However, I've yet to hear of any bad complaints since.
There are now three primary schools in Ardee - one boys, one girls and one mixed.
The boys is the Monastery N.S on the main road across from the church - on the right coming from Dublin. It would have been run by the brothers years ago but is now all staffed by lay-teachers.
The girls - Scoil Mhuire na Trocaire is on Hale St. (take a right after the boy's school coming from Dublin. It's right beside the convent and in my time was run by some extremely efficient nuns. It has had a lay principal now for a few years and similar to the boys school has a great rep.
The last within Ardee is an Educate Together school but I may be wrong on this. It is housed on the Ardee - Dundalk Road (N52) on the left, after taking the right fork past the Christ the King statue at the bottom of the town (I'm even confusing myself here!). I have no info on this school at all - it used to be the Church of Ireland school when I was a kid and had a good rep also at the time.
Note: Ardee is quite a wide catchment area so these three schools service the town of Ardee plus the surrounding townlands within about three miles. Outside of Ardee, the smaller townlands such as Stabannon, Ballapousta, Philipstown, Tallanstown each have their own primary schools which might be closer depending on where you decide to settle.
Can't help at all the montesorri front - but this should give you an idea at least!
C71