I'm rather new to this and am slightly confused about which direction the electrons actually flow. Using an LED with the knowledge that conventional current flows out of the cathode, and hence the opposite is true for electron flow, it seems electrons actually flow out of the ground pin. Is this correct?
Do electrons flow from the ground pin? Yes.
Does it matter? No.
Do you have to connect the LED the way the diagram shows, or backwards? The way the diagram shows.
Because electrons flow from the ground instead of the +ve supply, do you have to connect the LED the opposite way to the way everybody else connects it? No, the same way as everybody else does.
Positive to negative current flow was established before the discovery of the electron by J.J.Thomson in 1897. We still use the convention for most practical electrical and electronics but we keep in the back of our heads that the charge carriers are actually electrons moving the other way.
Figure 1. Diode, Zener, LED, photo-diode, SCR (thyristor), NPN and PNP transistors all point in the direction of conventional current flow.
All of our diode and transistor symbols show use arrows to show the conventional current flow.