Above Average - Excessively Difficult
Normally my comments are point-form but your proposal requires a long-form response. This is way too ambitious and we need to talk about what you are intending to actually implement and what you intend to let libraries implement for you. Unless you have done this before, or something of the same magnitude, you may have bitten more than you can chew. My specialty is in control theory and robotics, and uh... I'm pretty sure balancing is hard. At least if you care about handling disturbances. Unless you already have experience in robotics and control I would dissuade you from building a bipedal robot and instead consider some variation that doesn't involve balancing controllers.
You could, for example, not have it dance using its feet.
Please See Me Sometime*
10 / 10