The second to last sentence in Ordinatio Sacerdotalis answers both questions.
I declare that the Church has no authority whatsoever to confer priestly ordination on women and that this judgment is to be definitively held by all the Church’s faithful.
Not only can women not be ordained as priests, but the bolded above makes it clear that one cannot dissent from this teaching. Many hold that it is not an ex cathedra statement and hence is not infallible, but this response to a dubium on the issue holds that the male priesthood is an infallible teaching as part of the ordinary and universal Magisterium and St John Paul II merely reiterated what has been in the deposit of faith from the beginning. As Pope Emeritus Benedict XVI said in the response (while the head of the CDF), “[t]his teaching requires definitive assent…”
Between Pope St John Paul II and Pope Emeritus Benedict XVI you have both the greatest Church philosopher and theologian in recent memory agreeing that not only is is not possible, but it is contrary to the faith to hold opposing views. The phrases “definitively held” and “definitive assent” are keys to the fact that this is considered to be a matter of faith that cannot be disputed.
Cardinal Ratzinger also provided a letter along with the affirmative response to the dubium titled “Concerning the Reply of the Congregation for the Doctrine of the Faith on the Teaching Contained in the Apostolic Letter Ordinatio Sacerdotalis” if you are curious.
It is odd to me that it is almost 23 years to the day since Ordinatio Sacerdotalis was promulgated and nearly 22 years since the CDF confirmed that it is something that **must **be believed that people still talk about it like it’s something that could (and perhaps should) happen.