How do you know when you will need a bounce reflector? You'd be surprised that you end up using it frequently.

In close situations, the lighting from a direct flash tends to be a bit harsh. Bouncing the light (or defusing it with a device like the Sto-Fen) softens that light and distributes it evenly on the subject. The pictures above look quite professional with the soft, even lighting. The snap-on diffuser like the Sto-Fen allows you to aim the flash gun directly at the subject without overwhelming the subject with light.

The use of the fill flash outside is to compensate for the uneven lighting by natural sunlight so a subject is more evenly lighted - no shadows. Many professional photographers frequently use the fill flash when shooting close subjects outside.