There are two versions, one for 32 and second for 64 bit. If your version is for 32 bit, it will not work in 64 bit computer.
You don't. 64-bit Windows is completely incompatible with 16-bit programs. Besides, Adobe Photoshop 4 is, what, 10 years old? It probably doesn't run right well on recent 32-bit versions of Windows, either. If you desperately need to run it, install a virtual machine with an older version of Windows on it. Windows 98 and Microsoft VirtualPC should do fine.
Yes it is for both versions 32 and 64 bit, but Photoshop Elements if you mean that. Adobe Photoshop 8 is not compatibile and will never be. See related link for additional resources.
I don't think it makes a great deal of difference. Occasionally, Adobe will release more advanced versions for Windows before the Macintosh version (for example, the 64 bit version of Photoshop is only available for Windows), but for most purposes it works well on both systems.
Yes it is for both versions 32 and 64 bit, but Photoshop Elements if you mean that. Adobe Photoshop 8 is not compatibile and will never be. See related link for additional resources.
My 64-Bit version of Adobe Photoshop CS5.1 takes up about 418MB on my HD.
this might be a bit more help http://www.digitalartform.com/archives/2005/06/digital_color_m.html
Adobe Photoshop Express is meant to enable its user to edit pictures taken on mobile devices, like an iPad for example. Because of that its functionality is a bit limited, but more than enough if one is looking to use this software for that purpose.
They aren't quite the same program; Elements is aimed at home and educational users, CS2 is aimed at professional image manipulators. Because of that CS2 does things that home users don't need; CMYK colour models, support for teams working on the same image, support for high depth (32 bit) images.
Your question is a little unclear as your mixing terms together that don't go together! You need a x64bit version of Adobe software to run on a x64bit machine. There was no 16bit Photoshop, it was 32. Or do you mean a 16bit colour image inside Photoshop? Just because you have a x64 compatible processor, this doesn't give you x64bit computing, you need a x64 version of your OS, either "Xp pro x64" or a "64 bit vista OS". The only version of the creative suite, that Adobe support, as far as i know, in x64 is Adobe CS4. So No, there is no such patch to make pshop7 run on a 64bit OS, the whole architecture and addressing is totally different. Hope this helps!
Yes it works perfectly on Windows 7.
Yes you can, Photoshop 64 bit have exactly same options and tools as Photoshop 32 bit.
Switching from 64-bit Windows to 32-bit would require purchasing and installing another copy of Windows. This is generally not necessary, anyway, since the 64-bit version can run 32-bit apps just fine.