The 95-97 are much more modern and upgraded. It doesn't seem like a 15 year old car at all. All the little ditails are worked out and the overall quality is a step up. (Hard to imagine anything better, I know!!) The only slightly better thing about the 93-94 is the engine internals are slightly beefier, which really only matters in turbo applications. The post 94 are interferance engines make about 10 mors HP, so a little better N/A performance. So unless you plan on a twin turbo job, buy a '95+.
You cannot swap the nak and pioneer systems period. the stock pioneer is better than 80-90% of other cars factory systems so you really dont need to. BTW the pioneer is much more durable than the nak.
Spirted driving and the LS are hard to combine. That i know for sure. Good summer tires are about the best thing you really can do. Splitting the stock Y-pipe and making a true dual exhaust will also help. The brakes are ok stock but i put EBC pads in and that helped a bunch. i also have cross drilled and slotted rotors going in tomorrow which should also help.
AVOID AIR SUSP. AT ALL COSTS!!!!!