at the back you need to do a disc conversion, there are no drums that I know of which are 5x100 that swap on. you may be able to get some redrilled, but that would be a bit of a pain
5 stud front hubs wont fit 4 stud shafts, need to change the outer c/vs to 5 stud ones at the very least or just change entire shafts if thats easier for you. a couple options for 5 stud:
1. press 5 stud hubs into 4 stud bearing carriers, allows you to leave all the rest of the running gear alone, just swap outer cvs. problem here is either need to redrill 4stud discs, or fit 280mm setup and buy early passat b3 vr6 discs:
357 615 301 A - 280 brake disc, 5x100 - 38.83+VAT
2. fit 5stud bearing carriers complete with mk3 gti wishbones and roll bar
3. fit 5stud bearing carriers but use later passat 5 stud wishbones which allow you to keep your old roll bar