I would do the radiator fluid to.
As far as the OME springs go, Personally I would go with the HD springs but thats me. do you have plans for aftermarket bumpers, winch etc.. if you don't already? Do you have a hardtop? The more weight you add the more your springs will sag. The HD coils will give you a stiffer ride and they will probably give you a little more height than the 2" or 2.5" there rated at. To put it short, get the HD coils if you have accessories and a hard top and the medium coils if you don't plan on bumpers, winch, and all the goodies.
The medium coils will do you fine even with accessories they just won't give you as much height as the HD, but like I said the HD coils make for a bit of a stiffer ride.