I don't know why, but I'm having trouble finding a lot of this information. Also, I don't understand this either, but when I pull up the console with tilde in multiplayer and type a command, it comes out as a chat message instead. (i.e. if I type "quit" in the console in multiplayer, I just say 'quit' in public chat, but if I do the exact same thing in singleplayer, it quits out)

The manual only has a very brief listing of commands, and cites the main website as a source for the complete list. Despite the site still being up, I'm not finding anything. Anything else you think I should know would be appreciated, and as far as I can tell, the GOG installation and extras don't include any of this expanded info. Thanks in advance.

In single-player the console will always work fine. However, in multiplayer it can be locked out by the server administrator. Why might this be done? Because console commands can result in cheats and exploits. So, if your console isn't working properly in multiplayer, try using a different server.

I haven't actually done much multiplayer outside of LAN play. I see the console tickbox now, but it's been unticked this whole time, so the console should've been enabled.

One thing that confuses me is the save system. Can you not save on the map screen? When I finish a level and choose the save\load menu, I can only load files and 'save' is grayed out.

I'd afraid I'll have to get it installed again in order to check this out, but I do plan to get it installed some time soon anyway. From the sound of it, could it be that once you've completed a level it saves the level unlock progress to your game profile so that it doesn't need to save using the save/load menu, therefore meaning that the only purpose of saving is during a level?