When you launch the game and get the unity launcher, you can click on the input tab and change the weapon selection to what ever keys you like. Still there is no select next weapon option yet.
My first playthrough I didn't even know about the Seamoth and built the Cyclops first. I thought this was backwards and that you should have to find Cyclops parts before it was unlocked in the fabricator...
I would love to see a 3d wire-frame map that you revel through sonar pinging. I would say there would have to be a downside to active pinging like it attracted larger predators or something.