Re: Where has Scott Summers gone?
Easy. Jean lost control of her ability to hold back Scott's beams. For whatever reason Phoenix interferring, her getting distracted, not doing it right, etc. not important. Scott started to feel pain, and his beams returned. He blasted her at point blank range. Jean by reflex reflected the beams back at him, just like in the dam. Scott got catapulted back into the woods where he had one hell of a landing. Painful but not fatal. Jean was also knocked back from the rocky ledge and either hit her head or passed out from the shock. Since her powers are also reflected from her emotions, the sudden shock caused all those things to start hovering in the air including the water which turned into fog. And there you have it. There's about 20 different variations of this, either written up as script rewrites, discussions, fanfics, as well as a full-color comic page.
And of course Jean wouldn't remember what happened. Her brain was scrambled as it was from the shock of dying and resurrecting. what happened with scott would have been traumatic and confusing for her too.
It's also the simplest solution. No need to get Mr Sinister, Bishop, or anyone else involved. No need for time travel, magical dragons, or glowing crystals.
He'd never believed in life after death until Jean had died, and he still wasn't sure what he believed, but he believed in something. Maybe he just believed in her.
Jean: Mom says the only way I can cook is over a bunsen burner.