It really depends on what you're using it for. If you're a beginner, I suggest using Ubuntu or any of it's many derivatives. If you are using an older computer, perhaps Damn Small Linux. If you wish for the operating system and all applications to be compiled specifically for your machine, you may wish to use Gentoo. If you are working in a corporate environment, perhaps Redhat Enterprise Linux is right for you. Once you've chosen there is nothing forcing you to stay with the choice. You can always change, at little to no cost.
Many Linux distributions are intended for home users.
BlueCat Linux is a distribution aimed at embedded systems (self-contained devices). Typically, you would find this distribution used in devices like MP3 players, print servers, etc., and would not be installed on your computer for general use.
No. Red Hat is a commercial Linux distribution geared toward business use.
mint, ubuntu, debian
There are several good distro's of linux, it really just depends on what you are trying to do with it. ie programming, regular desktop use, or trying to run a server. One of my favorites is debian, but if your a new user I would suggest ubuntu or opensuse.
Linux is not an operating system by itself. Just like you cannot install Windows you have to install Windows XP or Windows Vista. You can use the website in related links to find a list of active Linux Distributions. If I could recommend one I would recommend Linux Mint because it is easy to use.
Yes. BackTrack is a Linux distribution that focuses on penetration testing and computer forensics.
Slackware Linux is an advanced Linux operating system designed for easy and simple use as well as great stabilities. The idea is to make a Unix-like Linux distribution and provides many development tools and features for those who like to web browse and those who want additional programs.
No, Ubuntu is part of Linux.
Yes.
Ubuntu is a Linux distribution (as in a specific OS setup with the Linux kernel.)
Yes, you can. It's called dualbooting. I guess with Linux you mean a Linux Distribution like Ubuntu? Check the related link if you want to know how.