Ubuntu can be installed on a Mac or run from a LiveCD (See links below). It can be run on a virtual machine on top of Mac OS X.
You could easily download Chrome for Ubuntu OS. It is available on the Chrome website as well.
Linux Ubuntu and Apple Mac OS
When you first install Ubuntu, it will walk you through the steps to install it and keep your other OS installed. Then when you boot your dual-boot system, you can simply select Ubuntu.
Unless you choose to install Ubuntu over another operating system during installation, Ubuntu will not delete anything from the other OS.
Legally Mac OS X can only be installed on computers made by Apple. Some people have had success installing it on other computers.
Go to the apple menu, choose about this mac, the version is listed under the apple logo.
Yes absolutely one can install Ubuntu or any other OS without internet connection. Of course you have to have the Ubuntu .iso image file handy. You can install it using USB stick with universal USB installer or from the hard disk you have downloaded to. But the latest updates won't be installed without internet.
No, Some of the laptops come with their own OS like Macintosh(Mac) OS used in all Apple's laptop. Rest all the laptops can run with Windows XP regardless of the hardware used.
Re-install OS using the Install CD bundled with the laptop.
Yes, iMovie is a software application that runs natively on Mac OS X. Technically speaking, that means you could install Mac OS X on a non-Apple computer and install iLife from there, but Apple does not support such actions.
Linux.
Do you mean, install Ubuntu and not enter the BIOS? To install Ubuntu using a CD, you need to enter the BIOS, setting the CD drive as the first boot. Otherwise, the computer will still boot off the hard-drive and ignore Ubuntu on the CD drive. If you meant, install Ubuntu without removing your Windows operating system? Then you need to set up a dual-boot between Windows and Ubuntu. Search the internet for fuller instructions on creating a dual-boot. If you simply want to try using Ubuntu without making any changes to the OS already on the hard-drive, either use the CD containing Ubuntu as an ISO file, known as a Live CD. Or, look up WUBI on the internet. Wubi will allow you to download and use Ubuntu as you would any other Windows file - without making any changes to the hard-drive.