For an SE live axle, the rear axle will probably be from a Mk2 Escort. There's a *slim* chance it's a Mk1 but only a slim one.
For an SEi with independent rear suspension, you will have bespoke Westfield aluminium uprights with either a Ford Escort diff in a bespoke Westfield aluminium casing, or a Ford Sierra 7" diff.
Driveshafts will be either modified Ford Escort or Ford Sierra as appropriate. Rear discs will be the FRONTS from a Mk3 Escort, and the calipers will be Ford Sierra.
On all models that aren't one of the SDV variants, front brake hardware will be will be Mk3/4/5 Ford Cortina upright with Cortina discs and Cortina calipers. The calipers are known as M16's.
Ford wheels have a PCD of 108mm as already mentioned.
The wheel spigot (the centre bit) is 63mm give or take, and asuming I remember correctly.
My usual advice when buying wheels is to buy the numerically largest offset (usually ET37) and make up the difference on the car with hubcentric spacers. Having the wheels all the same means you can rotate them around the car (asuming the tyres are all the same size... mine are...) when they start to wear. As it is with your wheels, the fronts are the fronts, the rears are the rears and if you have directional tread patterns then you can't really swap them from side to side.