S4?
if so:
three torx screws in each wheels arch liner front edge.
pull the fog grills out from the inside edge, on the underside of the bumper bar (top inside of hole now grills are out) you will see a hex bolt running vertically, one on each side.
bumper is no sitting on two front mounting points and the side wing clips. should be able to slide it forward and back and inch or so to show it is loose. if not you have missed a screw in the arch.
don't be tempted to wrench it off at the wings like many DIY's tell you.
Kneel at the right front corner, with your left hand on the back edge in the wheel arch get ready to pull the trailing edge away from the car.
With you right hand and a large flat head screw driver, reach in and you can see the edge of the clip where the bumper side clips onto the wing hanger.
prise the bottom clip open gently so you don't break it.
now pull trailing edge out and it should come away easily without bending anything or breaking the plastic clip.
repeat on the other side. useful to have some card for the bumper to rest on when on the floor. it is pretty flexible.
Do you mean re-ALIGN or re-LINE? if it is align then you can adjust the points it mounts on the wing and on the front posts, its a case of trial and error when it comes to getting it spot on.
Roof bars are a headlining job that I wouldn't touch personally.
need to pull all the associated trim on the pillars and pull the headlining out before getting to the screws,
I hate those jobs as they alwasy break! you can get a kit of interior panel removing tools from machine mart which help, but you still need three hands and eyes on stalks!
good luck
