Originally Posted by NorthStyle

If you've read around on here, just about every single topic you brought up has been discussed in detail. For example (I'm numbering them based on the order you asked):

1. Adjustable arms are highly recommended, even when using lowering springs. Are they necessary? That depends on how much you plan to lower, but if you're going to do it, do it right.

2. A corner balance isn't necessary unless you heavily track your car, then I'd say to get one done. An alignment should always be accomplished when changing suspension components.

3. Cost will vary from shop to shop. If you have the tools to do it yourself it's not difficult. I didn't, and paid $500 for my shop to install coilovers, front control arms, rear toe arms, rear camber arms, eccentric lockout, get it aligned and change my oil. They also routed my air lines from the trunk to the front suspension (cup kit).

4. Comfort is subjective. All of my cars for the past 10+ years have had coilovers so I'm used to them. The stock suspension on my Nismo left much to be desired in the realm of "comfort" so my coilovers were an upgrade in that area. This isn't always the case. My Lexus is stiffer, but still plenty comfortable to me and the wife.

Street and track settings are up to the individual so you will hear something different from every person. I set mine up depending on where I drive and adjust over time until I find the best setting that suits me.

5. Once I set the height I usually leave it. Adjusting the dampening is as simple as turning a knob.

6. Life span varies. My Fortune 500's on my Lexus are at approximately 30k miles and ride fine. But I don't track the car outside of an occasional drive on the Nurburgring. The Stance SS+ Pro (or whatever they're called now) have been on the Z for less than 500 miles so too new to comment.

7. Tire wear will depend on driving habits and getting a good alignment. Which goes back to #s 1 and 2.

A recommendation I've learned is to always ask if springs/spring rates are available and to speak with the company you're purchasing them from to get a recommendation based on what your intentions are. I always suggest purchasing Swift springs when available.

Hope this helps some.