I had all the power before 99.9% of other people and also had the car as "standard" with all the power at one point too. Admittedly mine was a Leon Cupra with the bigger brakes, but its my opinion that having big power on standard suspension, drivetrain and brakes (Cupra Brakes) is both doable and safe.
However, looking back, the mods I would consider necessary aside from the power are:
1) Engine Mount and gearbox mount upgrade as it reduces wheel hop which breaks components.
2) Uprated springs and possibly dampers - I had Eibach Sportlines on standard shocks and they were fine, but Eibach Coilies were good too. Reduces pitch and lean.
These are the only two things I would add with power upgrades - never tried an Ed30's brakes in ernest but you have to think about this simple fact with brakes - the standard car does over 150mph. Stage 2+ may add 15-20mph more. Realistically, is anyone really going to be driving at those speeds on a regular basis to need better brakes unless you do track work? Bigger power does not make standard brakes any less effective. Therefore in my opinion a brake upgrade is really not neccessary, but remember I am really only used with the 345mm brakes.
Its my personal opinion that unless you plan to track your car, don't bother with Anti Roll Bar Upgrades, and I have to say I am not convinced the Anti Lift Kit is really necessary either as the standard bushes do the same thing as the WALK pretty much. In addition, having had a Wavetrac Limited Slip Differential, again, I would not say that is entirely necessary unless you are intent on going from A to B as quickly as possible, and if you were, I would advise getting an S3 if you want a car with the same engine. You no doubt would lose accelaration after 80-90mph, but usable power at lower speeds will make up for it. In a straight line on the move after initial take off, and the Ed30/Cupra will take an S3 assuming a dry day.