Hello, I'll try to answer all of your questions !
We are working on a gameplay trailer. Stormland is kind of realistic so we don't have magic, zombies or steampunk stuff.
We plan 2 game modes : Campaign where you go from island to island building boats, and survival with a randomly generated map where you try to survive as long as you can and build a big village, staying on the same island.
There are no fighting ; you have to survive the natural disasters, and manage the group of survivors (feed them, give them a shelter, maybe later manage wounds and diseases).
We're still balancing data a lot. Storms will not be too frequent, more a big threat to overcome sometimes.
Farming will be very important in the long run. You can also fish.
Currently we don't plan to handle water, the villagers don't need to drink, but if players really want it why not ! Your desalination ideas are interesting. Could be great to use salt to preserve food too.
Right now the maps are on a temperate climate. We hope we'll be able to make more assets for other climates ! And for the volcano, well... That could be an end-game challenge.
Thanks for your interest in Stormland !