The Limits of the Taxing Power

An interesting question emerges from one of my comment threads on whether or not congress should be able to use the taxing power to get over limits on its enumerated powers.

1)  Can Congress enact a $50,000 tax on second term abortions?

2)  Can Congress enact a $50,000 tax increase, which is then rebated to anyone who does not have an abortion?

3)  If not, why not?  I don't want to hear any arguments about the social side: how necessary abortions are, how women would just have terrible back room abortions, how tragic this might be for women forced to carry a child to term.  Nor do I want to hear any arguments that this doesn't involve interstate commerce, as of course abortions are frequently purchased across state lines, while in many places, it is illegal to buy insurance from other states.  Presuming that Congress is agreed that abortions are bad, and they want to discourage them, why shouldn't they be able to use their taxing power to enact a ban that they could not enact more directly?

4)  If yes, they can, how long do you think it will take before Republicans enact one?