I don't think Trump is interested in the abortion issue.  Whether abortion is legal or not, a woman whom Trump wants to have an abortion will always be able to get one. When Chris Matthews asked him about his putative evolution on abortion, it was clear that he had not thought about it for even five minutes. Matthews lobbed a softball, and Trump muffed it.
I think his nominations to SCOTUS -- like every decision he makes -- will be filtered through the prism of the family business.  He will look for judges (and probably find them, too) who are sympathetic to his business interests and who will not be inclined to interfere with his privatization of the presidency: he has begun the process of folding the presidency into his corporate empire and his family. Trump has no discernible political philosophy; no core beliefs or principles, at least none that can be deduced from his public life. The one constant in his life is his passion for Donald J. Trump.