can my brother, who is an attorney in NV, act as executor and probate attorney for our mothers will? Do I need my own attorney?

The Will directs who the executor is.  If your brother is the named executor he has the control over the accounts.  But he must file an Inventory and Appraisement of all assets in your mother's estate.  The statute provides time limits within which this must be done. As a beneficiary, you are entitled to notice of the inventory, sale of assets and to accountings.  You have the right to object if you believe he is not acting appropriately.