Who will I take: depends who is available at the time.
Will repopulate the world with an awesome cult.
Weapons would be tricky, I don't have very much ammo for my handgun. Would have to acquire and develop better weapons with trips to the mainland, and depending on what characteristics the zombies have.
The number of zombies would be at an ideally low number, as most facilities on Alcatraz are abandoned/disused. I doubt theres 20 people on Alcatraz at any given time.