Coming from FCP I like to mix audio using a hardware control surface, where levels are recorded on a clip basis. In Premiere it seems audio changes through the software mixer are recorded on a track basis. Is it possible to record audio level changes via the mixer direct to the clips, so when I move the clips I keep the changes? Or can I only use the pen tool to manually draw in waveforms if I want to dip clip audio up and down?
Welcome to the forum.
As you have noted, the Audio Mixer does record Keyframes at a Track-level, so those automation changes are retained on the Audio Track, regardless of whether the Clip(s) are later edited.
The Clip-level Keyframes are done in the Effects Control Panel, pretty much as you are doing in the Volume adjustments in the Timeline w/ the Pen Tool, but with a difference - the Slider in Volume>Level will dynamically add Clip Keyframes, as you playback.