Exercise 2 solution

(a) Rushed snapshots to send straight on: JPEG. It is small, opens anywhere and needs no conversion step.
(b) Difficult high-contrast scene to edit heavily: raw (or both). The article says large corrections show fewer artifacts on raw data, the bit depth is greater, and white balance can be set later.
(c) Very limited card space: JPEG, since raw files are typically 2 to 6 times larger.
Shooting both is also reasonable when you have the space. Which choice suits you is partly personal preference; the points above come from the article's comparison.