Justices are judicial, but the nomination and confirmation process is political, so that political considerations are a part of who is selected when. I suspect that, for republicans, since democrats always go after their nominees like rabid dogs, the nomination process is even more discussed in a political sense.
The best qualified potential nominee may not be the best qualified nominee that the President believes the team can get through the senate, two different things. That a President may actually believe a particular candidate is more qualified, but believes that candidate will serve the greater goals of the President, if held back in anticipation of a particular justice leaving the court is just good politics. And nominations of justices is political...
Absolutely. Republicans have to pick candidates that are hard to Bork. Bork was a very qualified candidate. There was no reason to have turned that into the circus it was.