firstly, yours is non edc. if it had the edc (electronic diesel control) then you wouldn't have a throttle cable.
the bit on top of the injector pump is the remains of the egr (exhaust gas recirculation) system, which looks like it's been removed, or just disconnected. Have a look on your turbo, if you have a strange looking mushroom shaped object on there, with a steel pipe running to the inlet hose of the manifold, then the egr valve is still in place.
as for the missing spider, that's a mystery, unless it's already been removed in the past, and the bypass fitted.
the non starting problem does sound like the immoniliser not playing, although it could also be a dodgy starter relay, or even a dodgy starter motor. does it turn over quickly when it works, or is it quite lazy sounding - almost as if the battery is low on charge?