the gearknob will simple screw off, there is many wheels that will fit. the 16" 5-spoke zetec wheels are popular and cheap. if you fit aftermarket alloys with low profiles you want at least 17" because 15's or 16's with low profiles look a bit gay on a big mondy. 18's look better on them, but really need a set of lowering springs to stop it looking like a range rover.

you need an offset of between ET35-45