lots of the discussion about chokes, shot, and sights centers around hype. It makes a slight difference on turkeys at the edge of range. For a new turkey hunter, just get out there. Learn the patterns, the roosts, the strut zones, etc. Learn about turkey behavior, and how and when to call. These things make far more difference in killing turkeys than the choke, shot, or sights.
To answer your questions, get a good tight full choke. I shot the factory full out of my 10 ga BPS with good results, and now I shoot a 3 1/2" 12ga 870 with "super full" or "ultra full" or whatever it is. I shoot hevi shot 4s 5s and 6s, they all work. I've shot lead to, it works. I've never used anything besides a vent rib because I can't figure out how you could miss a stationary target with a 12 ga pattern. I think it's more likely that a sight would get knocked off center while crawling through the woods than that I would miss a turkey because of the inaccuracy of a vent rib.
Just my opinion, I know lots of people love debating and patterning, and comparing. If you're the kinda guy who likes "stuff" go for it. I like to keep it simple, and I can tell you from experience, you can kill plenty of turkeys without ever missing all that crap.