few queries regarding CS to RA conversion

[Bendyknees]

So spent the day strippin stuff off the motor so i can see what im doing and making my shopping list. few questions

1. water pumps. i want to use the pulley and altenator off the cs engine as the pullies on the ra water pump an alternater are damaged. but they list 2 pumps for the 1.6 diesels. whats the differance between then? reason i ask is my cs is early and the ra is late

2. Uprated clutches. have seen black diamond ones but who else is about and how much tougher are they.

3.egr valve. can the standard plastic housing cope with a bit of extra boost and do u connect it or just blank it off.

4. While ive got it apart do i change the oil pump, bigs and mains or do i leave it with the originals. im torn between the two. if it aint broke dont fix it. but im not sure its not broke....

5. turbo downpipe. is the standard jx downpipe restrictive or will it be ok? only gonna chop it about to fix my race can, but would rather fit big bore if available.

Also does anyone have a haynes type pdf or whatever the brand with tourque settings and clearances ect?