when i had alloys for my 106, i had to use spacers.
basically, it went car, spacer, alloy. a spacer is a small round disc that goes on just before the wheel, therefore making the wheel further away from the car.
as for the effect to handling.. i couldnt say, although as the wheels are further out, i'd guess it'd improve handling. not sure though, it's just what seems logical to me. waynne will probably know.
cost me £20 for a set of two (i only needed them for the back)