more questions

The local short line here has over the years gone from owning and maintaining their own locomotives to "leasing them from a sister corporate company". Hasn't exactly been a smooth change, at least from my non-expert viewpoint. So with that in mind, I offer these questions:
1. Presumably there would be a guarentee from the locomotive vendor (the commission in this case), that a certain number of locomotives would be available each operating day. Is this practical ?
2. Who pays for the costs incurred from a failure on the road ?
3. What happens if equipment is abused during operation ?
4. What happens if the equipment is not maintained in a manner not suitable for use ?
Having watched the heroric efforts over the years to run trains every day, I wonder if it is really practical to have the operator and locomotive maintainer be two separate entities. Like how many times did they have a failure on the east side of the line which necessitated sending a crew out of Chama with a fresh engine at 2AM so it would be in Antonito in time for the 10AM train ? I don't see that happening if theirs not a good agreement for who covers those costs!