I don't use AutoFill so I can't say, but it doesn't sound like you've tried it in Chrome either so it'd be worth giving it a shot before shrugging it off. I don't see why such a similar feature would be lacking in their more-so masterpiece project than in their addons. Besides, why would you have to fill out the same form twice? That'd be a pretty stupid feature if you ask me.
EDIT: Reading about it, it does only fill out forms you've done before..? That's really, really retarded. O_o But it sounds like they're working toward a more toolbar like version.

With bookmarks, yes you are missing something...you can easily make folders from the Bookmark Manager or the Edit menu after you add a bookmark with ctrl+d or by clicking the star to the left of the omnibar. At least I assume you're looking for categories or something? This would fix it..

I'm not sure what the share button is so I can't really address that, sorry.

Bookmarks are insanely simple, and pretty awsome,
I must agree though, auto-fill is somewhat lacking, but im sure there working on it.

My only guess for share, would be, it would send the link to your facebook/myspace/ect accnts, so others can find that url.... but thats just a guess XD