@Mayadome Thank you for the super guide!
I would like to note that it IS possible to get the Assault/Automatic Shotgun as Chris. As Richard is eaten by Mother Neptune, he will drop his weapon. Once you drain the tank and go down into it, it'll be near the first smaller shark that you see.
Also, the Wind Crest is acquired by completing the bee puzzle in the Researcher's Study, not the tiger puzzle. The tiger puzzle gives you shotgun shells for the blue stone and an MO disk for the yellow stone. BE CAREFUL not to put the red stone in the tiger's eye or you will spring a trap!