Movable crate and a transforming cube

Just need some code ideas on how to make a pushable box (basically my idea was when I right click it would move it 1 block in the direction I'm facing, ie: if I'm facing north then when I right click it would move the block north by 1) But then 1 problem came up and that's the fact that if there's a wall in the way it would replace the wall, not good for puzzle maps.)

And then i wanted to make a block that changes textures (or just replaces it with another block) when powered Redstone is connected to it.

Any tutorials or ideas on how to make this possible?

Thanks , INPS.