Assuming you have at least a 2nd generation iPod Touch (1st generation iPod Touches do not support iOS 4.) simply plug your iPod Touch into your computer and open iTunes. You will be automatically prompted to update your iPod Touch. If not, find your iPod on the left hand side. Click your iPod and your iPod's information will open. Click the button labelled "Check for updates" and your iPod Touch will be automatically updated to the latest iOS version.
There is no such thing as 'installing' an iPod Touch.
no
You can install free text messaging apps, but you have to pay for minutes to call people on the iPod Touch.
No, however the ipod touch 4g has two cameras on it
Nope. Only 3GS and iPod Touch 3rd gen. get all the features. iPhone 3G and iPod touch 2nd gen. get a lot, but not some, such as multitasking, because the hardware is not suited for the "massive" RAM
you cant
No
Sometimes depends if the apps that you install have bugs
safari should already be on your iPod touch. it is a default app that cannot be deleted.
You first have to download a torrent of the version of firmware you want, and then you can install it onto your iPod touch
You probably need to make a itunes account
In order to start using your iPod Touch, you must first download/install iTunes onto your computer and sync your iPod Touch to iTunes.