Hi there, thanks for playing!
1 - You should be able to switch to windowed mode by hitting ALT + ENTER at the same time. Although I can't guarantee you'll be able to scale the window appropriately.
2 - Not in the foreseeable future, sorry - Time to work on games is rather sparse for me currently, eventhough I orriginally intended to add a two player mode. Just out of curiosity: Would you prefer having a split screen for two players or have both players share the default view without a splitscreen?