type 9 gerbox + diff info

[Shorty]

Looking for a bit of info regarding the type 9 gearboxes + diffs.
Engine will be 2.0 zetec

Basically what setup is best regarding gearbox and diff ratios and is there a way of identifying the ratios.
Are all gearboxes the same if it be from a 1.6 or V6? If not what would be the best option?
Same question for diffs really, are they all same fitment and what ratios are available and best option for roadster.

Just want to make sure I know what im looking for