My Patrol recently developed an identity crisis........started leaking oil onto my garage floor, it suddenly seems to think that it is a Land Rover!!!

Anyway, some investigation revealed that the rear crankcase oil seal is leaking, and needs to be replaced. Since my 4.2 has a turbo fitted, I figure that it is a good idea to eliminate high oil temps as a possible reason for premature failure of the oil seal, so I want to fit an oil cooler.
Can anyone who has been through this process before point me in the right direction in terms of what I need? As far as I am aware the conversion will entail the fitting of a sandwich adapter at one of the oil filters, and then using some hydraulic couplings and piping to connect to the new oil cooler.
My main questions:
1. Are sandwich adapters universal, and if not how do I figure out / specify what I need?
2. Bearing in mind that space is somewhat limited (by winch and front mounted inter-cooler), what size oil cooler do I need?
3. Which oil filter is the best one to use to fit the sandwich adapter to?
4. Are there any Cape Town suppliers for the above, or will I need something ex JHB?
Any advice appreciated.
Many thanks,
Ross