Push-ups and shoulders

Hi, this might be a beat-to-death topic, but I have a technical fine-point question about the push-ups. Specifically the shoulders.

In what way and at what point do you rotate the shoulders?
-Do you try to stay externally rotated all through out and emphasize it at the top position?
-Or do you internally rotate at the top to activate the pecs and lats and then rather externally rotate at the bottom?
-Or do you externally rotate at the top and internally rotate at the bottom?

I'm not talking about elbows here, as I assume they should always be pointing with the inside forwards, especially at the top - like locking out on rings.

Also, how much do you planche at the bottom during PE2? You start out stacked vertically with no planching, right?

I'm asking cause one of the coaches at the gym today gave me a tip that I was too much in external rotation and losing tension in the pecs and lats. That seemed like sound reasoning. So, what is the best way to perform PE2?

For Pe2 have your first knuckles in line  with your sternum. Pressing straight up from there should be enough planche.

As for rotation. You don't really need to emphasize it, but if you're going to do it you want some external rotation on the way up and relaxing back into neutral on the way down. If you really want to see how much tension you can have in your chest with external rotation. Just hold your arms out straight like you would for scap shrugs. Externally rotate your hands so fingers facing to the sides. With elbows locked press forward as hard as you can from that position and see how that feels.

For me I feel my chest even more so.

1. Push ups in the course material are generally for the sake of developing the pressing strength of your triceps, other pressing related muscles in your back, and some pectoral development. 

2. Through out the full range of motion hold your core muscles tight and keep your elbows close to your sides.
At the top position externally rotate your upper arms, flex your triceps, and protract your shoulder blades(aka: scapula).
At the bottom position, hold your overall body position as level as you are able. 

When you have a moment, read the following thread... Proper Push up Form

Alright, I appreciate the answers. Thanks! When you have been doing a movement for quite some time, you get more interested in the details to polish it