fyi _ is a built-in motion; that plugin defines a couple others: il and al, which are specifically characterwise (vs. _ can be either that or linewise)
gq is a linewise operation anyway, so gq_, gqil, and gqal all have the same effect
> Triple-clicking in Terminal.app will select from the previous \n to the next \n (i.e. it will select multiple lines if the lines are wrapped), while triple-clicking in iTerm2 will select only that line.
In iTerm2, toggle "Triple-click selects full wrapped lines" in the Pointer tab in Preferences.
> When you start typing a command-line in Fish that matches a previously-typed command, it automatically shows the rest of the line as an available completion, and pressing ^F or the right arrow will complete it for you.
^R is more powerful, though; it matches at any point in previous commands, not just at the beginning.
> The lack of this functionality actually really kills my ability to use any other shell.
You can achieve that behavior in readline (which is used by bash, python shell, etc.) by changing the up/down arrows from previous-history/next-history to history-search-backward/history-search-forward. In ~/.inputrc:
gq is a linewise operation anyway, so gq_, gqil, and gqal all have the same effect