It is recommended that you replace the struts/shocks when you lower your car. Yes, your car should be fine in the short run with those lower springs but they will quickly destroy your shocks/struts. If you are replacing your struts anyways, just get the FRPP shocks/struts, do it right the first time and it will save you work and money in the future. It will also handle and perform better, so the right way means replacing shocks/struts at the same time
You do not need to add a rear sway bar but if you do not have one, then adding that will be beneficial to your overall handling. I suggest a 21-22mm rear bar and poly bushings/endlink bushings. If you do not have the mounting for one, Steeda makes a kit that allows you to attach one.
I also went ahead and moved this thread to the suspension section.