Symptom 1 is a sign of a bad manual driver
the rest are just signs of age. Most of which are easily fixable. Any mechanic/auto elec should be able to sort out the door.
10k is not a bad price for a GTS4 that came in under the old CPA scheme, and isn't on the verge of a coronary like some of the 15 yr old ones that people pick up cheap to make money on.
What's the rest of the car like, interior, panels etc? rust? bends, dints, dents, scratches?