The City Manager shall be chosen by the Council solely on the basis of his executive and administrative qualifications, with special reference to his actual experience in, or his knowledge of, accepted practice in respect to the duties of his office as hereinafter set forth. He shall be a full time official of the City with no outside business activity. At the time of his appointment, he need not be a resident of the City or State, but during his tenure of office he shall reside within the City.