How do automobile batteries differ from deep-cycle batteries? Which should be specified for a solar ...

Ans. to #1

Standard automobile batteries have thin plates and are designed for high starting currents. Deep cycle batteries have thick plates and are capable of deeper discharge cycles, so they should be specified for solar electric systems.

Ans. to #2

Life-cycle costs include all expenses over the expected life of a system. By using life-cycle costs, the system can be compared with alternatives including conventional systems. The initial cost of solar energy systems is usually higher, but may have lower operating costs and have almost no energy cost.

Ans. to #3

The charge controller regulates and limits charging current to prevent overcharging batteries.

I know you spent a lot of time finding this because I swear it wasn't in my textbook

You're partially right, it's found midway in the chapter, but not at all easy to find. Good luck with the rest