Brother,
Cultus VX comes with a rear defoger. If there is no defoger in the rear, that means, a changed rear Screen probably from either sher shah(Karachi) or Bilal Gunj Lahore.
Coming to the A/C.
I beleive Cultus 2005 came with a Deso AC which is good. Normaly people get a Sandan after market A/C fitted which in comparison to Denso is not good enough.
Stereo does not matter. In any case the cultus VXR stereo sucks.
Remember one thing when buying a car.
There is a universal formula: an average car does 25000 to 30000 Km per year. So no matter how good a car looks take it for granted that it has done around that in terms of millage. 25000Km-30000Km into the number of years.
Yes exceptions are always there. As U say ur friend is selling it I am sure he wont pull a hard one on you.
Do not pay more in exchange of very good condition, because the loss is always made while buyimg the car not selling it.
If U buy it make sure U pay the right price.
TC
P.S. Get it checked by a good Mechanic if posible.