1. 1200 MS points.
2. I'm almost done with the game and I started playing from 1 PM to 6 PM with breaks in-between. I'll let you know my total playtime when I get 100% of the items (I'm at 75%, it's going to be easy). It's a game with good replayability (for the gamer points mostly, but just like any Metroid/Castlevania game really).
3. Nope.
4. They're OK, lots of great lighting effects. Don't forget that the scale of the game is different, this one features little characters that can't have that much details on them (kind of like in Bionic Commando Rearmed).
5. It's worth it, easy 200 points game. This is what I wrote in another thread: It looks and plays a bit like Metroid and Castlevania, but the simplicity in the placement of items and stuff is just not that "complex." It also doesn't feel like everything is attached in an intelligent manner. Sure, you can go outside and enter different areas of the whole place, but I don't have this "feeling" that they've really thought about creating a good pacing with the exploration and stuff.
Still, the game is fun for what it is! If they do a sequel I'll play it.
Have fun!