You have to remember that flight instructors don't get paid much - it may well be better to use the money you have to hour build rather than do an FI course. An M/E rating isn't that hard to acquire and might be a useful first step. But you do need at least a CPL, so I would get studying, although some airlines don't like self-improvers. Do you really want to fly airlines? Fire fighting sounds like fun, but you will need a float rating for that, and it's a very long road.
You're right about staffing though - I know at least one major airline that could do with copilots but they aren't allowed to hire them.
Phil