This is something that you need to do NOW. If your brother still have his mental facilities then the easiest way to do this is to meet with a lawyer and your brother to draft the extent of your power of attorney.
No. A person must possess legal capacity to execute a POA. A person who has dementia lacks legal capacity. You must petition the court to be appointed the legal guardian.
Your brother must execute a Power of Attorney document voluntarily. The POA must name you as the attorney-in-fact. Your brother must have legal capacity to execute a POA. If he is incapacitated then...
No. Generally, a parent executes a power of attorney in order to give another adult the authority to make decisions for their child for only a short period such as when the child will be in the care...
No. A POA cannot be transferred from the holder to another individual. A new POA or guardianship order will have to be obtained through the required legal procedures by the person seeking such.