Off the top of my head the FZ6 doesn't have adjustable preload as standard. These adjusters will give you very little in real work feel and they'll will not be matched to the fork damping, you may as well add a stack of 2p on top of the spring.
As for redound damping again the fork isn't fitted with this option as standard. The whole damping unit, would either need replacing or serious re-engineering to have it adjustable which wouldn't be worth cost, if you could get it done.
If you really want a fully adjustable front end, you need to look at fitting something from a R6/R1. It may be possible to just change the whole front end, yokes/forks/calipers/wheel etc, but this would need to be carefully checked. I don't know of anyone doing that mod, to an FZ6, probably as it's just not worth the cost/effort and it will just emphasise how bad the back is.
If you just want to improve what it there, look at Hargon or Hyperpro springs. Again any improvement you make to the front will expose the rear shock, as standard they are crap. You could replace that too and then you'll have a sweet handling bike once properly set up for you but not cheap about £700 ish.