Don't know about any of the other stuff, but from what I've read, his smoking is/was 7-8 cigarettes a day. NOT good, but hardly heavy smoking, which implies more a pack or two a day. That is, of course, if that 7-8 is anything near the truth. Which is anyone's guess.
I'd find it hard to believe that he could do the workouts he does (which seem to be uncontested) if he had years of heavy smoking under his belt, though.
Oh, and about his academic performance, I don't think Harvard is easily tricked in to electing someone who needs extensive tutoring as president of the Harvard Law Review. Did you mean that insinuation to be as nasty as it sounded? I hope not.
Biden's health is a concern, but less because he's not the top ticket - he's the backup. McCain's health is a greater concern because he is
the top ticket and the backup is polarizing, at the very least. Even among the Republican party - it's not just liberal pinko scum who question Palin as VP. Many many longstanding Republicans are not happy with Palin and are not voting the McCain ticket in part because of that nomination. Colin Powell is just the latest. (Of course, there are longstanding Democrats who aren't going to vote for Obama because he's black.)