The story/plot progression is about halfway planned out, and once I figure out a plot twist or two the rest should be cake.
Your character will progress through the game just like in any other rpg. You will level up, get stronger, learn new skills/abilities, and get some helpful items along the way.
Some(or all) of the abilities include
Pounding (similar to the pounding in Yoshi's Island on snes)
Certain equip items are planned at the moment as well.