Is this necessary? I'm new to android and recently bought a factory unlocked samsung galaxy note (European ver). I heard all this wonderful thing about rooting android phones and what exactly is rooting? and does it boost my phone performance? Will it brick my phone? and Do I need to root it to get free apps? (like jailbreaking on iphone) or it's fine just the way it is?
I have the GNote too so I'm gonna start off with a warning. Unfortunately for us, the GNote ICS kernel has what has been called the super brick bug. This means that the kernel has a bug that basically destroys the data structure of your bootloader when a data wipe (factory reset) is made with the stock kernel installed. I suggest you read up on it, before even attempting to root your phone.
Secondly, rooting will not instantly boost your phones performance, but it is a key that leads to that doorway. Rooting will allow you to flash a custom rom and kernel that will allow you to overclock and undervolt your CPU both boosting your phone's performance and giving you better battery life at the same time. This also allows you to install a ROM with zero bloatware to take up resources. Just don't expect it to have the SPen apps, although some custom roms retain them, most don't. You have several options, CyanogenMod (CM9 or CM10) being the most popular along with a plethora of other ROMS.
Will it brick your phone? Maybe yes, maybe no, hopefully not. To be honest, as I discussed above, the risk of bricking your phone is a lot higher on the GNote than other devices although no rooting method is 100% risk free -- all has a certain amount of risk. So do it only if you are confident on your research and ability to follow and understand instructions to the letter without thinking you are better than the developer who discovered the rooting method and take a couple of short cuts.
Free apps -- you get the same free apps from the play store (rooted or unrooted). Unlike jailbreaking, afaik, rooting is not a key to getting free apps. There are tons for usable free apps in the play store anyway.
Lastly, yes the phone is fine the way it is. If you are uncomfortable with the risks, you have a great phone anyway.