It was politics. He knew the best way to get him confirmed was to have Myers go up first to appease the Dems. And then when she cratered because of the Conservative Republicans he could get his person confirmed. Not a done deal but i think he will get confirmed.
ALMOST no chance that's the case. Bush has taken a beating from both sides on the Miers choice, with allegations of cronyism, ineptitude, etc. Alito's ability to get confirmed is unchanged whether he's before or after Miers. IMO, anyway. Politics WILL determine is confirmability, but those aren't any different with a failed Miers nomination in the mix.
John Roberts got an easy confirmation from the Democrats because he was conservative but not a right-wing ideologue. Also he was replacing another conservative. But Alito is replacing the Court's only moderate. Alito has a distinct reputation for conservative legislation from the bench that will make him a bigger target for criticism than Roberts. His confirmation will be much more contentious and he will not be able to get away with generic answers as Roberts did and Miers attempted.
I think he at least makes it to a vote . And as far as answering questions the Democrats sort of screwed themselves when Biden and all of them during Clinton advised her ( Ginsburg ) not to answer any question that might give away opinion on how she will vote. The Republicans are using that against them. I dont happen to agree with it. I think a Supreme Court nominee can talk in hypotheticals on opinion in order to express their views on how they interpret the Constitution. This is too important of a position to not have to answer questions.