Nothing herein shall require any changes in plans on construction or the lawful use of any building or structure or land existing at the time of the enactment of this chapter. Although such use does not conform with the provisions of this chapter, the foregoing provision shall apply to any nonconforming uses therein or created thereby; provided, however, that the nonconforming structures or uses shall not be:

Zoning permits shall be required for nonconforming uses existing at the time of passage of this chapter and shall be issued by the Zoning and Code Enforcement Officer without charge, stating that the use is nonconforming. Registration shall be preceded by a notice from the Zoning and Code Enforcement Officer to the property owner that the use is nonconforming. Upon receipt of said notice, the property owner shall apply for the above permit within 30 days.

Abandoned uses shall not be reestablished after discontinuance for a period of six months from the date of cessation or discontinuance.

A structure shall not be rebuilt, altered, or repaired after damage exceeds 75% of the structure at the time of destruction, except in conformity with this chapter.

Nothing herein contained shall prevent the strengthening or restoring to a safe condition of any part of any building or structure declared unsafe by the Building Inspector from complying with his lawful requirements.

A building, or use, constructed or planned in compliance with existing laws prior to the adoption of this chapter shall be deemed a legal nonconforming use, provided that: