Debian based OS based off Ubuntu 8.04. Slight kernel modifications. Said to be faster than Ubuntu.
Linux is free. Windows and Mac OS X are not
chmod +x is the command to set the executable flag in Linux but, Linux does not use exe files.
It's a command to start the X server for running Linux in graphical mode, if you have any of the desktop environments and/or window managers installed.
Assuming you mean a super form called Ultra Sonic, No
Latex is a 5 letter word. It begins with L and ends with X.
The same thing as networking in Windows or OS X: The system by which Linux will be able to communicate with other computers.
Yes.
Linux to Windows: There is no relation at all aside from both being created for the same hardware initially. Linux to OS X: Technically no relation. however OS X is a full Unix-compliant operating system, meaning it actually does a lot of things very similarly to Linux.
Project A
This is the problem, no one really knows. Unlike Windows or OS X, Linux doesn't really have you "register" or phone home to anyone, so no statistic on how many Linux users there are is accurate. I personally estimate Linux users number at least as much as OS X users, though many will not agree with me.
Root
Mac OS X is based on BSD, which is similar to Linux. Because of this, it is fairly easy to port programs between the two operating systems. However, the two operating systems are not the same, and programs for one don't work on the other. Linux also uses the X window system, and Mac doesn't, though Mac has a program to support programs that use the X window system. Because of this, Linux programs can be configured to run on Mac OS X with a little elbow grease, but not the other way around.