OK, I'll take a stab at answering.
1) Yes, I think marijuana (and most other drugs) should be legalized. First of all, banning them doesn't seem to work very well; secondly, I think people have the right to do what they want with their own bodies; thirdly, it seems obvious that legalizing and regulating drugs would eliminate most of the violent crime associated with the drug trade. That said, I haven't really taken any action because it's not an issue that I care passionately about. If North Carolina were to have a referendum tomorrow about legalizing marijuana (dream on) I would vote yes, but I'm not going to campaign for one because I have things I'd reather be doing.
2) No, I don't think alcohol and tobacco should be banned -- for the same reasons outlined in my first answer, but also because I use both of these substances. I DON'T use any illegal drugs (for reasons completely unrelated to their illegality), and so I have a hard time working up much personal passion where these drugs are concerned. I'm an occasional, social smoker and giving it up wouldn't bother me all that much, but if somebody started a movement to ban alcohol, you can bet I'd be campaigning against it for all I was worth. So I think it basically comes down to a numbers game: as soon as a majority (or a significant plurality) of voters have a personal interest in seeing marijuana legalized, it will be legalized. At the moment, people who use alcohol and tobacco generally come from demographic groups that vote, while people who use marijuana do not.
Don't know if this is the sort of answer you're looking for, but that's my two cents.