other than the cobra I don't think there are any of the performance kits that do not require some kind of spacer. My baer kit I can't remember I thought only needed an 1/8" but it might have been 1/4". As long as they are a quality hub-centric spacer and as small as possible I don't see a problem. I would get concerned if they were any greater than 1/4" but a solid spacer with the correct studs should not hurt.
It really depends on how you drive. Just cruising like 99% of the population, stock brakes may be fine. If you sometimes accidentally find yourself running 80 in a 40, you need upgrades.