
THAT IS NOT FITTING FOR EXTERNAL OIL COOLER! It IS THE OIL COOLER! You connect water coolant hoses to that outlets. It cools oil with engine coolant when hot and also warms oil on cold starts in winter (diesel needs long time to heat engine oil to working temperature, that is why oil-water coolant is best solution for this engine )
If you can, put it on it will be all you ever need on a car with that kind of gearing. Also check oil cooler for leaks when you buy it, even new ones can leak. If you have money you can get bigger oil-to-water cooler from modern TDI engines, but I think that would be overkill for what you need, oil will never get that hot while offroading (and if it does you just back of a bit, right?

)
2. 1.6 td steering pump can be fitted to the engine, but first check if there is enaugh room in engine bay, I am not familliar with samurais (but I do have suzuki swift 4x4 gti waiting in the shed

) If there is no room you will probalby be making you own brackets. ( I think there was engine conversion kit for these conversions, check the web)
3. If pump was standing for long time pump vanes can sieze. It's easy to change the pump on the car if you can get to it (again I dont know samurai)
I would try it on car first, if it works you can tune it at home to about 130 hp.
If you take it to ordinary pump mechanic I he will probably try to rip you off, atleast that's my experience with them...
If you have cash just send it to Giles, that way jou can be sure for reliability and power (and he is fair guy)
I would rebiuld it alone if I had to do it again, I am superpissed with the shop that did mine (they couldn't even do GOV mod and didn't bother to ask me if they should replace worn out piston, $&%$

4. Every decent diesel shop should be able to test your injectors for cheap, also you can make you own tester from truck jack (dont know the right name)
It's best to just get new original GTD injector inserts, they are not that expensive.
Also naturally check if 1.6 are the same as 1.9 on outside, I don't know for sure as I only did 1.6 head (for now).
EDIT: also be super careful when bolting injectors into head, head can crack easy on injector threads. Hold torque wrench with both hands when you do it.