I've had a great idea for changing recruiting, to allow managers to sort and hire based off psychometric testing, proprietary ranking algorithms, and financial guarantees, rather than looks or networking. However, #2, I don't really _love_ to sell, but I've done it (telemarketing), and #3 I have trouble focusing or finishing and rely on J-types for that. Also, I'm working on another project so don't have time.
You say you want to start with the perspective of the candidates, but are the candidates paying? Your real customers are companies. They are the ones paying. They are your customers. You will end up catering to them.
Embedded job listings (like AdSense) is a novel concept I haven't seen yet. It has potential.