Welcome to the Club!
Appears you've a good project going. Seems there is a lot of Zetec support on your side of the pond, which is good.
The bell housing is one which mates to the Twin Cam engine, which uses a ford block, and most of the holes line up with the Zetec.
RaceTech makes a "inline" cast oil pan, which may help with starter mounting, although it's a little pricey.
Dean & LotusJoe have mounted the starter at different bell housing locations, something you'll probably look at in the future
(that's where I'm at now)
As far as the S2 frame/Zetec fit, maybe scour the Yahoo Europa group knowledge base and photos - a lot of info there!
Enjoy