The invalidity of any section or provision of this bylaw shall not invalidate any other section or provision thereof.

No provision of this bylaw or amendment thereof shall affect any permit issued or any building or structure lawfully begun before the first notice of hearing thereon before the Planning Board was given, except as provided in Chapter 40A of the General Laws, and any amendments thereto.

When this bylaw imposes a greater restriction of the use of building, structures or premises or requires larger yards, or open spaces than are imposed or required by any regulations, or permits, or by any restrictions, easements, covenants or agreements, the provisions of this bylaw shall control.