the seats would fit if you are a bit handy with a welder. to make golf mk3 seats fit you have to chop off the inner leg ( i think) and weld it in closer, so i assume the same would be for this.
the audi calipers and carriers would fit, assuming you have late 16v hubs, but the discs would be the wrong stud pattern. i assume the audi ones are either 280 or 288mm so you'd need g60 discs/pads if the calipers/carriers are ok.