For a discussion of the Skip by Leading Text Wrap preference, see Chapter 18, "Text Wraps: The Good, the Bad, and the Ugly."
For a discussion of the Text Frame First Baseline Position options as well as Align to Baseline Grid, see Chapter 16, "Everything in Its Right Place: Using Grids for a Clean, Structured Look."
A handy shortcut for increasing or decreasing the leading of a selected range of text is pressing Option+Up Arrow (Alt+Up Arrow) to tighten the leading or Option+Down Arrow (Alt+Down Arrow) to loosen the leading. The amount is determined by the value in the Size/Leading field in the Units & Increments Preferences. To increase/decrease the leading value by five times this amount press Cmd+Option+Up Arrow/Down Arrow (Ctrl+Alt+Up Arrow/Down Arrow).