> Downloaded Dir Opus 4.16,tried to install and installer gives me error
> Is an Amiga 1200 AGA version I think.

There's no such thing as an "Amiga 1200 AGA version" of programs like Directory Opus.

> Can I install well 68k software on my Morphos and later run it as
> embeded 68k software inside MorphOS 3.18?

Yes, of course. That's how you can run ARexx scripts on MorphOS, after all :-) This works for almost all system-friendly m68k software.

> Why ultimately all of my Installer programs failed when i try to install things
> like MUI classes and lately this Dir Opus 4.16 filemanager version?

Depends on the error message. You can try InstallerLG, which is said to be more compatible in certain situations.