Yes, you can instruct without an instrument rating, most PPL instructors fall into that category.
Will jobs flood in once qualified? Probably not, if you had 1000 hours or more instructing they might do, but the first job may require a little more effort.
Will it stand you in good stead with the airlines? Yes, it will give you the edge over someone who is not qualified.
Can you live on the pay? Clearly some do, but its a matter of how big your overheads are. PPL and Commercial instructing are quite different from a pay perspective, but you have to start at the PPL end.
Is it worth it? Of course it is, many regard it the top rather than the bottom rung as you put it. Many airline pilots instruct at weekends and when they retire. You can do it at almost any age provided you can pass the medical.