At that age you should replace the complete parking brakes, brake shoes,
springs and the bowden cable.

First aid is lubricate and adjust the bowden cable. The break shoes can
be adjusted through a hole in the wheel center.  Use a lamp and a turn
screw.

No. You should bleed and drain all the old brake fluid out. Change all your
brake fluid... front and back.

Another thing is it is possible that your rotor is too mirror smooth and bad
brake pad.