Welcome to the forum you'll find the members on here are a friendly and helpful bunch 🙂 I'd recommend a diagnostic check to see if any fault codes flag up. Best taking it to darkside for this as they've done lots of work on it already.
Looks a good project. Could it be injector seals rather than the injectors?
I'd recommend doing a full service. Check the brake pads, sometimes the wires and sensor that warns of worn brakes can in fact break.
As long as you buy a bumper from.same year or close to it and same engine (so exhaust tips the same) then you should be fine 🙂
Euro car parts might give you the exact model. Sorry for delayed reply by the way
I'd always recommend buy the best you can afford.
I'd recommend buying from a dealer and look at taking out an Audi extended warranty if possible/available. Only an Audi one though not a 3rd party one as they're usually not worth the paper they're written on.