You don't have to change the balancing shaft chain if you really don't want to. But consider that when you replace the timing chain you've done 98% of the work required to change the balancing shaft chain - so you might as well just do it.
The oil pump should be OK as long as you've done regular oil/filter changes. You can always disassemble it while the timing cover is off to inspect it.
A rattling Vectra = chain very close to death 🙂