[jor]

There is no other pump on the d24, the bosch takes the fuel from the tank. If it's not working apparently it's usually due to seals, here's a link to a chap that repairs engines, way over my head, but the photos are terrific; thosbryant.wordpress.com/2014/11/13/volvo-d24t-bosch-ve-injection-pump-re-seal/
I do have an old pump, but it's been lying a lot longer than 3 years, so is likely to be in as bad a state as yours, the simplest thing might be to take it to the local injection place, after finding out how much it would cost to reseal. Be extremely careful when removing the pipes as finding replacements will not be easy.
Finding the cause of the oil leak will involve removal of oil pan and various gaskets and according to the books is an engine out job. Apparently the d24 pump differs from the d24T one, if you want to check if the Tic is different again I would suggest asking Barry /Bernard at Lakes Volvo (breakers). I think all their 940 diesels have been pillaged however. Again I do have a d24T lump in the garage, so if the T and the Tics pumps are the same it could be salvaged....

jor