Is there a hotkey I've not found to draw patterns with transparency? (i.e. white does not turn black pixels white when using patterns)

Patterns are always opaque, but you can "flatten" them into pattern 0/1 (transparent white/black) by using "Edit -> Invert" twice on a selection.

Depending on what you're doing, you may also need to turn on "Style -> Transparency", which controls whether selection movement/pasting treats the selection as transparent or opaque.

The other feature to be aware of when working with transparency is "Style -> Transparency Mask", which displays transparent pixels as a mid-tone gray to distinguish it from opaque white. With Transparency Mask mode on, the white color in the palette is opaque white, instead of transparent white.