Leave Apple Magic Trackpad 2 plugged in charging? Is it okay to leave the Apple Magic Trackpad 2 (late 2015) plugged in via the Lightning cable? 


Is the battery-charging smart about not over-charging/over-heating?
Are there any other pros or cons to leaving it connected to my Mac via the cable? Does it run faster/better or slower/worse? Does it use the cable for communication rather than Bluetooth?


The manual merely mentions that you can use it wirelessly after charging via the Lightning cable.
You should discharge your battery about once a month to recalibrate it. Other than that there should be no downside to keeping it plugged in. The battery charging mechanism is smart about not overcharging it.

See this page by Apple: Why Lithium-Ion?