Some questions from tonight

[Scrapper1]

Rule questions:

What has to happen for a screen to be called? Is it a screen if the serve just happens to go over the player(s) at the net? Do the players at the net have to have their arms raised or anything? Do they have to be standing right next to each other?

Player moves toward the net to play the ball. She completes the attack hit well below the height of the net, but can't stop her momentum and continues to run and contacts the net. Is this a net fault? Or is it considered to be no longer playing the ball? For full disclosure, my partner at R2 did not call it, and I called the net fault from the R1 position. But I'm questioning it now.

Mechanics question:

Is there a preferred "posture" on the stand as R1? I generally rest my hands in front of me on the stand. But I saw pictures of an official I respect a lot, and he stands with his hands at his sides during the rally. Any thoughts on presentation?

I think that's it for tonight. Thanks.