Allright, I've made a few changes to the input mechanism. The WCA scrambler works for all cubes I've tested.Edit: Another thing is the notation. On 3x3x3, I think using M, E, and S, would be better than "1R2, 1L, 1B' " type moves. Also, instead of 2F, 2F', and 2F2 on 3x3 scramble notation, you should use B, B', and B2 respectively. Same with how you use 2U, 2U', and 2U2 instead of D, D', and D2. On the moves you have done to the cube, it is fine, but the scramble notation is kind of weird. Wide turns would also be nice to add.
You can paste a scramble into the TextBox and hit ENTER to execute it. I think it works for all cubes up till 11x11.
Make sure you set the correct cube orientation before.
I'll work on the other stuff you mentioned such as the middle slices.