First of all, I love StarTropics. Played it as a kid. So I decided to play it again a while ago. But of course, I've forgotten some things. Like, I often get this "Magic Bottle" but I have no idea what it does or how to use it. Also, I'll find a Snow Man every now and then, but once again, I have no idea what it does. If some would please shed some light on the subject, I'd appreciate it greatly.
The "Magic Bottle" is a potion that will restore some of your health when you get it. In order to use it, Pause the game, press up, use the D-Pad to select the Potion, then press A. Press Start again to un-Pause the game.
As for the Snowman Doll, it can only be found in one place in the game: Chapter 2 (just a couple of rooms before you get to Octo the Huge's room). The process for using this item is the same as the Potion. When used, it will freeze everything in the room for about 10 or so seconds. This item was made especially for fighting Octo the Huge.
I hope this helped!
On behalf of all of us here at C-Island, I would like to be the first to welcome you to the Island! Enjoy your stay.