
ealry mk2s had more slats on the front grill plus static quarter glass in the front doors. These changed to full wind down windows in about 86. Also the wing mirrors moved further down the door.
90 spec GTIs got big bumpers, side skirts and thinner bump strips on the doors. Drivers stayed the same as their pre-90 counterparts.
90 spec wiring affected all models. easy way to tell is the position of the hazard switch. on dash = CE1 early type. On steering column = CE2 (later wiring)
90 spec front seats are slightly different design too (the bolsters are a different shape IIRC)
No models had ABS as standard IIRC, nor PAS/elec windows/central locking etc
WIdetrack is usually acheived by using a mk3 front subframe inc the brakes and hubs (5 stud conversion if taken from a mk3GTI or VR6). The rear subframe can also be used for a slightly wider rear.
Mk2s dont often have rust issues but common places are around the fuel filler cap, rear boot plinth (behind the number plate) and under the rear bumper. I have seen mk2s with really rusty sills so check under there aswell. But usually they dont rust anywhere near as badly as the mk3!!