1- use the packing only on rear. not front, you will need to adjust the headlights beam to acommodate for forward tilting of car.
2- not really,
3- no.
use properly and accurately machined aluminium / stainless steel (for long life) spacers
you will need 02 spacers ( one for each side) they both should be of EXACT SAME dimensions.
jack up the car from the rear. remove wheels, LOOSEN all the suspension bushes so they can rotate freely.
take off the shock absorber, and fit the spacer. now place a jack under each wheel hub and jack it up slowly until the car is resting on its wheel hubs and the springs are compressed due to weight of car.
NOW tighten back all the bushes. fit the wheels and you are done.
you can also fit the spacers without loosening the bushes, but in a short while you will have worn out bushes.