In hindsight, Romney was the best GOP choice for November 2008. He wasn't the best GOP choice in January 2008, though, so he didn't win.
Maybe, but then you would've eliminated the GOP's best chance (among current likely candidates) to win in 2012.
Romney would have been a good candidate in 2008 because, at the end of the election campaign, all anyone cared about was the economy. Romney was all about the economy, and actually had real, tangible experience where Obama and McCain clearly had none.
He's wishy-washy as all hell when it comes to social issues, but that would have been largely irrelevant.
And for what it's worth, unless the economy is still in the dumps in Nov. 2012 (God help us if it is), Romney will be a terrible candidate for President that year. He's a niche candidate.