Primary Teaching was 500 in Maynooth last year, 470 in St. Pat's so it'll be somewhere between 470 and 500 I reckon. Best of luck, I want Primary Teaching as well but I only needed to resit Irish to get a C3 to gain entry as a Mature Student. I hope it all works out for you!
With it now a 4 year course in Mary I it will probably rise 20 points I say. As more students studying in the college less places are been given to new first years. It used to be a 3 year until 2 years ago and so they could take more students in every year. Most courses in all colleges will probably rise though as college applications have risen on last years figures. Hope you get the points to go study it in Mary I. Mary I is a great college. Hope this helps.