Yes, you can already do that... I have windows 8, but i have been experiencing alot of driver issues. I would definitively wait for the public version to come out. It will probably come out this Fall.
it comes automatically as an update in windows 7 if it is available. Use windows update to install it automatically
Windows 8.1 can be downloaded and installed on a Windows 7 PC, but Windows 8.1 is not an update it is a new operating system. This new operating system can be bought from Microsoft for $119.99.
Windows Update.
It can be regarded as both. It is an update on Windows 8.0 and could be seen as an upgrade on Windows 7 or older systems.
You cannot, but you don't have to mind it as Windows 8 automatically comes up if you don't choose Windows 7 in 30 secs in start up. It's useful cause you can always come back to it.
Windows 7 systems requirements is where you would look. During Windows 7 one would use the Upgrade option and install an edition of Windows Vista to Windows 7. Windows Update in Control Panel will open and install Windows Vista if you already have automatic update turned on.
Via Windows update
Yes, Windows 7 comes with Windows Firewall in the OS itself.
the windows anytime upgrade tool
If you have windows 7 you can upgrade to it. If you have windows XP you will need to do a complete install.
connect your PC to the internet so that windows 7 can update
It means the computer comes with Windows 7.