whats probably leaking is the fluid inside your struts...they go bad the seals crack and they start to leak. Now when you say a full suspension setup...well the simple suspension setup is just new struts/shocks and new springs. Now to change the whole suspension system means replacing all of the mounting points and hardware...top caps, cups, tie rod ends, wheel bearings, stuff of that nature etc... Basically anything that is involved with your suspension system that moves would need to get fixed. If your going to go all out I would also replace all the bushings too. Now for strut bars and such, those are aftermarket add ons that make your chassis stiffer and reduce body roll thus making the car handle better and become more responsive...those pieces are best left to personal preference and style. But pricewise all this stuff replaced brand new at the cheapest...KYB GR-2's and stock springs...should be about 500 all told...at the most expensive...can run you in excess of 4-5k for a very very good suspension setup that is tuned properly.