My questions are How hard is it to fix the cable, and how hard is it to switch the whole lock cylinder on the trunk??
well seeing the bang up job you've done so far I'd say pretty hard
BUt in reality, the whole thing shouldn't be hard... just takes patience. And for prolly like $30 a junkyard would sell that stuff to ya. Just make sure if you get a lock cylinder off of a new car, you need to get the VIN to get a proper key made from Mazda.