The answer to all the points asked is - yes. (See links below)
== == I am not to sure, but it should be as long it is the same version or a newer version. IT MAY NOT WORK with older versions.
You don't have to install a newer version of Windows - however - you may have problems installing software designed to work with the latest version on older machines.
you have to remove the version of windows you dont want first
The best place to start is windowsupdate.com, if you current version of windows (down to xp service pack 2) is current enough windows update should do the trick for you. If you have an older version of windows you will probably want to buy a newer version of windows and start from scratch.
Videos made in Windows Vista will not work in Windows XP because the formats used to create the newer version of a WMM project are not available on the older version of XP.
Windows Virtual PC enables a PC user with a more recent version of Windows, (such as Windows 7), to run an older version of Windows (such as Windows XP). Windows Virtual PC can run right from the desktop and only for specific programs. Virtual PC was designed to eliminate compatibility issues with older software on newer Windows operating systems.
You have not mentioned which version of windows. In older version you may have no problem and in newer ones also you may run it in compatibility mode. You may also run it through DOSbox.
yeah the antivirus is only good for year because the newer version of windows come it will not accept the older version of antivirus as windows service packs, vista, windows 7
Windows 10 will not be free. You can upgrade to Windows 10 for free if you're running Windows 7 or Windows 8.1, but you'll need to pay for a license if you're running an older version of Windows or if you're upgrading from a free version of Windows 10. You can buy windows 10 be free from: Microprokey
You need to install an older .jar file.
Yes They Should Be Compatible With The Older Model.
windows explorer is an older version of my computer. windows explorer can be found in windows 2000 and older, my computer can be found in windows xp, vista and windows 7