alignment shoudl be unchaged. spacers might be necessary to correct the offset and to clear calipers.
imho: stay away from this, unless you are absolutely sure that the resulting offset will be correct. otherwise you can destroy bearings in no time (10 kmiles)
stagger, as understood by tire width, is not what you seem to be referring to. there is a "stagger" built in, in that the front and rear, as measured left to right is not equidistant (track width). this may or may not change depending on offset. if you keep the offset stock, the wheels will naturally be wider and poerhaps stick out more, but track will stay the same if measured between wheel centerlines.
the stagger as understood by the front tirewidth (not track) being narrower than the rear, is what gives the piggish handling to the 330 ipp or m3. likely, you would like to get rid of that.