Since I am on the will do I have a right to see it before mother passes away

No, no one--no child, no heir or beneficiary, etc.--has any legal rights in regard to a will before the testator (person making the will) passes away. Before the testator dies, the will has no power, conveys no rights, and is a purely hypothetical document (it may be changed or revoked; the assets described in it may be sold, transferred, lost, destroyed, etc.). After she dies, you can challenge the will if you believe it was fraudulent, etc., or the actions of the executor if you believe he is not following the will, and in that case would have the right to see the will--but not before then.
Moreover, YOU have no right to challenge what your brother is or is not doing with  your mother's finances. They are your *mother's* finances, not yours: the  fact that you are or may be in a will does not give you any interest in or right over her money and assets while she is alive. Your mother can revoke his power if she feels he is abusing it, and even sue him if he stole from her--you cannot. If she is mentally competent and is content with what is going on, that's the end of the story.
Remember, being in a will does not guaranty you will inherit: all a person's money or assets may be spent, given away, etc. before death, and being the will gives you no right to interfere in that.