Firefox
Ubuntu is a "distro" of the Linux operating system.
Yes, Ubuntu is an operating system, that uses the Linux Kernel.
Firefox is installed by default. To launch it, click Applications > Internet > Firefox Web Browser
You don't "install" Wikipedia. Wikipedia is a website you can access from any computer with a web browser, regardless of operating system.
Ubuntu - operating system - was created on 2004-10-20.
Ubuntu includes Mozilla Firefox by default. The web browser for Kubuntu is Konqueror.
Ubuntu is free, it can not be pirated.
Ubuntu Server Edition is a free and open-source operating system for use in servers.
You can use the Ubuntu operating system as you would use any other operating system! Unlike MS Windows, which is propriety and has to be paid for, Ubuntu is a free, open-source operating system that can be downloaded for free, and copied and given away as much as you like! I recommend searching Google for more info.
Windows 10 is currently a free operating system and can be downloaded on the Microsoft website, Ubuntu OS is also a free operating system, it can be Downloaded from the Ubuntu website Ubuntu.com/download
Ubuntu is a computer operating system based on Debian Linux and is freely distributed. Ubuntu wiki is a site which answers questions on this software.
Copies of Ubuntu can be obtained by downloading the disc images directly from the internet ubuntu.com, Internet mirrors and via Bit Torrents.