No. The gameplay will be expanded quite a bit. This game will have vertical scrolling and all sorts of fun platforming goodies. It will also have an equipment system that will allow you to customize your character's abilities and strengths/weaknesses. You'll have to play levels multiple times with different characters in order to find hidden items.
I would tell you if I knew. If we make enough money to pay people it would go faster. Right now things are slow with the team because of their jobs. I put a tentative date of March 2013... but that is just a random guess. I probably wouldn't expect it earlier than that though unless there is some miracle where everyone is able to work full time without distractions.
Don't forget we have to finish porting SMBC to Unity first also. It makes sense to do that anyway because SRS builds upon the features and gameplay of SMBC.
We plan on keeping the core gameplay similar, but we would like to add unique things to each character. If you look at how I modified the characters in SMBC, that will give you an idea, like when I added wall and ceiling jumping to SOPHIA III. The core will be similar, but we'll add our own unique flavor so that the characters feel familiar, yet new.
We have decided to omit SOPHIA because she is the most complicated character in SMBC and it would take a long time to get her working in SRS. We feel our time is better spent on balancing the characters and finishing the game. It is possible we could add her and other characters as DLC after the game is released.
We decided to add a stretch goal for our Eve VII, our character based on SOPHIA III. If we the goal, we will add Eve VII to the main game.