A power of attorney is a legal document which, when signed, gives one person the authority to do things, sign documents, conduct business affairs or make health care decisions on behalf of a second person, in the same manner that the second person would do if he or she was there. In this context, the word 'attorney' does not mean a lawyer - it means the person named in the document, who is also referred to in some jurisdictions as the agent or attorney-in-fact.
Your attorney has a fiduciary duty to you, and is required by law to always act truthfully, in good faith, and in accordance with your wishes, so far as that is possible, whenever he or she is representing you.
By its very nature, a power of attorney is necessarily a public document. If you are paying your attorney to act on your behalf, the terms of that compensation can be set out in a separate document, which will remain private between the two of you.