Thank you for your comment!
So there is an explanation for you not loosing a live when blowing up (it's actually explained in the tutorial :p). When clicking on the biscuit, you get points depending on the current multiplier, but if you explode you loose points (more than you would gain, still depending on the multiplier). You only loose a live if your score falls below 0, meaning you could explode for a small amount of "damage" but still live.
As to the 4 lives issue, yes I was conscious about that, but I should probably make that more intuitive and make it so you loose the round when all lives are gone.