(a) Yes in 2007
(b) No in '07, Yes eventually
(c) No, never
I'm betting the voter consensus coagulates around Choice B, which seems to me as bankrupt a choice as the voters could make. Essentially, Choice B is punitive, which doesn't seem to be the Hall of Fame voters' job. Who assigned them the role of morality police? (I've long argued that the BBWAA has no business exclusively bestowing Hall status, but that's an argument for another time.)
Voters' choice should be: In or out now? Worthy or not now? Not "Yes, he's Hall-worthy, but just not THIS year because we should make him wait because there's a good chance he was juicing." If you don't think he's worthy because of the taint of steroids, you should NEVER put him in. How will waiting a year change the taint, aside from totally undercutting the intent of the original statement?
My take: If I was a voter, I would vote him in right now, even though I suspect he was a cheating d-bag. The entire era is tainted; to single out McGwire because he's the poster guy for it seems unfair. History, not Hall placement, will judge McGwire and his peers, much like the way that most fans now mock the one-time conventional wisdom that McGwire helped "save" baseball, an analysis that no self-respecting fan or expert can possibly maintain.