The 10th Kingdom is similar, yeah, but I can see a lot of differences. These universes aren't two separate ones coexisting. The fairy tale kingdom came before this one. Ours sort of overlayed that one.
I dunno about the tunnels. I think only Henry thought it was a portal of some sort. I never actually heard it mentioned what was down there, just that he thought something was. And the shard? I thought that was a piece of the queen's magic mirror. I guess we'll find out eventually lol
I think the queen is just another pawn. She thinks she's ruling it all but Mr. Gold's the real puppet master. And if anyone remembers anything, betcha it's him and not her.