Not at all. It's very easy to imagine it going the other way. Midcentury liberals were all about extending human rights to new groups of people and I could reasonably see Republicans defending Roe for economic policy reasons in an only slightly different work.
Possibly, but remember during the 1972 presidential election McGovern was tagged as the candidate the supposedly favored "acid, amnesty, and abortion." I guess this is a sign that the Democrats were friendlier to abortion rights than the GOP even before Roe was decided.
It would have depended heavily on the state and type of candidate. The Kennedys were famously quite pro-life until they stepped into line.
You could imagine a mildly pro-life Southern Dem getting the nomination in 1992 when they were desperate after 3 terms out office and willing to make whatever deals they needed to get back in. They went with an economic moderate IRL, but no reason it couldn't have gone the other way.
Bill Clinton was a mildly pro-life Southern Dem. "Safe, legal, and rare" was a step to the right of where Mondale/Dukakis had been.
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