Subject to the provisions of the declaration and other provisions of law, a proprietary lessee:
1. May make any improvements or alterations to his unit that do not impair the structural integrity or the electrical or mechanical systems of any portion of the cooperative;
2. Shall not change the appearance of the common elements, or the exterior appearance of a unit or any other portion of the cooperative, other than the interior of the unit, without permission of the association;
3. After acquiring a cooperative interest of which an adjoining unit or an adjoining part of an adjoining unit is a part, may remove or alter any intervening partition or create apertures therein, even if the partition in whole or in part is a common element, if those acts do not impair the structural integrity or electrical or mechanical systems of any portion of the cooperative. Removal of partitions or creation of apertures under this subdivision is not an alteration of boundaries.