for any and all purposes(вариант с purposes встречается реже: The Author may from time to time appoint an agent to represent him for any and all purposes connected with this Agreement.4uzhoj)
in respect of all matters(Proprietor's Agent will be authorised to act on behalf of the Proprietor in respect of all matters arising out of or in connection with this Agreement and to sign the Agreement on behalf of the Proprietor.4uzhoj)