1) No serious problems, except for Personas that have been in an accident. Use logic and avoid choosing cars with broken carplates front and back like my abah .
2) Not too bad, but you have to rev over 2K RPM for acceptable acceleration from standstill.
3) If you have a rather heavy foot, check out my fuelly . Almost 100% city drive.
4) Extremely excellent. Makes other drivers who brake while cornering look sissy.
5) Better tyres, soundproofing, brighter light bulbs, front strut bar

I think it comes with one front and back. You can say that my foot is like a concrete slab I suppose. I don't really hit the highway, and when I hit it's usually clear, so... . I won't say the city FC is bad cause of my foot, but because of the short distance I travel daily (less than 5KM one way to my destination each day unless for lunch).

Has rear ARB.
TDU, on the side note, I don't think front ARB is used typically, front uses strut bar.

if you pedal hard, the engine downshift is normal

if you pedal hard, the engine downshift + engine check light is not normal

dont know wo, maybe the previous owner got install shift timer ? 

is the engine check light stay there for very long or once your car finish shifting it gone

Easy, check the ECU lor. Is yours Elegance model? If yes, most of us can help.

From cold start? Normal geh. Press more on the brakes.

What's the mileage? Ada tukar air filter, spark plugs, fuel filter, clean throttle body, etc........?