1) I beleive so.
2) Not legally. The Open Source portion of OS X is called Darwin and this operating system uses pieces of FreeBSD, although it's kernel is unique. Darwin is available for Intel. All of the software that makes up the OS X graphical desktop (Aqua) is proprietary and controlled by Apple, who only permit it to be used on Macs.
The GNOME desktop uses many ideas from Mac OS, and you may find it to your taste. GNOME is supplied with FreeBSD and most Linux distributions.
For what it's worth, the programming specifications for Aqua have been reimplemented to create the OpenStep graphical environment, but it is essentially a hobby for it's developers.
3) No. Linux has produced a large number of new UNIX users, and some of them also use BSD as well. OpenBSD is very well suited to routers and firewalls, and FreeBSD is an effective system for servers. Some people use these systems for desktops. Most Open Source software is cross-platform, and FreeBSD is the second platform after Linux. FreeBSD can also emulate Linux to run Linux-only software.