please explain how I can download the fft://fft... site you mention
Just download ftp://ftp.opera.com/pub/opera/win/1217/int/Opera_1217_int_Setup.exe. The link I previously gave you was ftp://ftp.opera.com/pub/opera/win/, which will take to you to the Windows section for downloading the old Opera (Opera 12 and below). you were supposed to click on the folder for the version you want, click on the "int" or "en" folder depending on whether you wanted the international or English-only setup file, and then click the non-x64 setup exe to download the setup file for that version. But, you can just click this new link to go directly to the setup file so you can download it.
4)Since I'll be moving from WindowsXP, 32-bit to Windows8.1, 64bit, will I need to insert the (86x)after program files?
You need to install Opera 12 to "C:\Program Files (x86)\Opera" (or "C:\Program Files (x86)\Opera 12" if you want). If you open up windows explorer on Win 8 64-bit and browse to your c: drive, you'll see 2 program files folders: "Program Files" and "Program Files (x86)". The former is for 64-bit programs and the latter is for 32-bit programs. Since you'll be installing a 32-bit program when installing Opera 12, you install to the x86 one.
If I understand correctly, if all of the above goes well, my browser (client) operamail will naturally be part of it; Will I have to reregister in "mail & chat accounts"? as imap?
If you copy the profile folders to Win 8 correctly and install Opera 12 correctly, everything will still be set up just like it was on WinXP. You won't have to create the accounts in Opera again or anything like that.
I just enabled Opera Link
Opera Link won't sync mail, so using Opera Link is not a solution for your case.
what would happen if I actually downloaded the 25 version now in a different folder, such as "my documents"? would that kill my existing version 12 which is in Program Files?
When you run the Opera 26 installer, just install it to "C:\Program Files (x86)\Opera Stable" and it won't interfere with Opera 12. So, you can test the new Opera all you want. But, as mentioned before, the new Opera doesn't have a built-in mail client, so you'd be using it only for browsing and would still use Opera 12 for mail.
Currently, my Opera is in Program Files, and I copied it from there into my hard drive
You don't copy the Opera program files at all unless you have a standalone installation/single user installer there in the Opera folder in the program files folder. You can tell by browsing to that folder in Windows Explorer and looking to see if it has a "profile" folder in it or not. If it doesn't, then you have a normal install of Opera and you don't need to back up the program files at all, only the local and roaming profile folders for that install.
Re your second move, my path does not show "local settings"
There's a local folder and a roaming folder on Windows. On WinXP, they're "C:\Documents and Settings\user\Local Settings\Application Data" and "C:\Documents and Settings\user\Application Data" respectively. On Win8, they're "C:\Users\user\AppData\local" and "C:\Users\user\AppData\Roaming". So, you won't see "Local Settings" on Win8 as it's just called "local" and you won't see "Application Data" as it's just called "AppData".
Note though that the folders are hidden by default in Windows explorer. So, you need to unhide them. On WinXP, you click the tools menu in windows explorer, goto "folder options" and then "view". There you'll check "show hidden files and folders" and you'll uncheck "hide extensions for known file types". On Win8, you need to do the same thing. To do that, search for "folder options" in the control panel, go into "folder options" and then "view". For the extension part on Win8, it'll be an option on the windows explorer toolbar.
So, in short, you need to back up the "Opera" folders inside the local and roaming folders on WinXP to your external hard drive, connect that drive to the Win8 computer and move/copy them from the external hard drive to the local and roaming profile folders on Win8 *before* you run the Opera 12 installer on Win8.
also, it's "all users: not "user"
When I mention "user" in a path, I mean "insert your username for your windows account". "All Users" is something different and not what you want.
I'd personally be very cautious about copying in a "full profile" from an old-system install onto a new-system Opera 12 installation. There are some path-specific entries contained in operaprefs.ini (in the "file types" and "user prefs" sections) that will likely not transfer directly into a new system's file mapping. Likewise, any other Opera file path references that might involve custom toolbar files, sessions, and such may not track properly onto the new system's file-naming.
Over the years, I've found a less troublesome method is to perform a full, new Opera install onto the new system, then (with Opera turned off), copy in to the appropriate, corresponding new folders/subfolders only those specific old profile files needed to 'customize' the new install like the old one (things like bookmarks, notes, toolbars, override, search, and wand files). I'd much rather manually re-establish a handful of custom user settings than try debugging a failure of the new install to respond to some particular operation because some pathname in an obscure copied-in profile file was now broken by referring to the old system's file terminology. I find it safer to use this method, and then open Opera in both the old system and the new and manually walk through all the Preference subpanel settings side-by-side to make sure they are the same where appropriate and refer to the correct paths for each system where/if that applies. It only takes a little while, but it avoids a lot of possible debugging grief later. In fact, I've walked the "same" Opera 10.53 version install across 7 different computer systems without problem, using this approach, and just two weeks ago, repeated it for an Opera 12.14 version across two different laptop systems.