1. Strange. Couldn't reproduce it. Maybe it's related to the template in the Data folder? xd_crash_info.txt would be helpful.
2. In the next version, I'll make it so that the second player is kicked back to the main menu when the first player leaves the game.
3. The colors of the participants should be marked with checkmarks, passwords should correspond to the colors, a newer version of HD may not be able to load password-protected saves made by an older version (in the next version, I'll add the ability to load old versions of password-protected saves in single-player mode, and for Multiplayer, I'll add a message with the required version if there is a mismatch)
Yes, everything is OK here; I didn't think to mark the colors with checkmarks.)