Also, if I, as Player 2, open the map, I won't be able to edit anything on it or place markers, either with the mouse or the gamepad

I don't know how it works exactly besides B41 is a waiting game and only shotguns are useful where as B42 is a point and click adventure game. 

Also, calendars (as well as other posters with pictures) would be a good decoration for the walls of the room.  

That's not right. You have the same RPG elements in B41 and B42 regarding character accuracy. You will have a crap damage output at low Aiming level while placing your cursor perfectly. The player and the character skills are separate.

No if you've already tried it then that's fine. This appears to be the same thing as an issue we've been tracking, at the moment we have no reliable way to reproduce it but it is something the devs are looking in to and the more reports we get like this the easier it will be, I will pass this one on to them. Until then the best advice I can give is to disable any overlays (NVIDIA, Steam, Rivatuner, MSI Afterburner, etc) and use more ram like you are doing. Or go back to the Stable branch as that doesn't seem to have the same problem.