hi Jingle
Nothing else needed for this kit.
Literally remove wheels, clean the holes on the hub with a cotton bud.
Apply some Loctite (drop) andscrew in the studs, torque to 25ft/ibs or 34Nm
Fit wheels
Screw nuts and torque as per standard 85-88ft/lbs or 115-119 Nm
Same as you would with bolts.
Just makes removing and fitting wheels easier.
http://ca-int.co.uk/items/WheelStudFittingGuide.pdf
Or
http://ca-int.co.uk/items/CAWHEELSTUDCONVERSIONFITTINGGUIDE.docx
As for you 25mm spacers, what type are you using? Do you have the spacer that bolts to your wheel hub and thent he wheel bolts to that?
If so then yes this kit is fine.
If you have a standard 25mm spacer and use longer bolts then you need a much longer stud and personally be it studs or bolts, that's not a good idea.
A spacer that big should bot to your hub then you bolt your wheels to the spacer.
Safer and les strain on bolts/studs