Does the shockwiz advise settings for specific models or just ‘add rebound’ ‘add pressure’ etc? If it is model specific does it cover recent and past products?

Just seeing if it’s worth hiring one for and old fork / shock set up?

Adjust this a little or a lot, this way or that. Not shock specific.

Not specific, but there are some forks/shock that it won’t work with, details are on the site I think

As above, check it’s compatible with your fork and shock. It’s not about age, just the type of air spring.