Are your current shocks old? Does it ride well?
ive only experience with coilovers but if you think it feel bouncy and under damped (oem shocks arent designed for stiffer springs and can often feel 'boingy') its up to you if you think new shocks are worth it really, theyl no doubt improve the ride.
as for bushes, id poly them all bar the front wishbone rear bush, just my preference, and my setup. Bushes dont necessarily make the ride worse, they just transmit more vibration really, and a little more noise, but the improvement in ride and feel is way worth it.
On oem shocks and lowering springs i dont think you'd regret it.