Joko, this is the rest of the answer I tried to post yesterday, but AB was playing up yet again, so I had to keep pruning it until I finished up with the response you see above.
If there were some evidence that �the bee's knees' was the very first of these phrases to appear, it might be possible that the others are merely variants. But there appears to be no such evidence.
The very earliest recorded uses of these in writing are very close in time. �The bee's knees' first emerged in writing in H C Witwer's �Fighting Blood' published at some point in 1923 and the first use of �the cat's whiskers' was in W A Roberts' �Saucy Stories' also published in 1923. Much too close to call a winner!
Both might have been around in speech beforehand, of course, but we will probably never know which was the original. As a result, the �business' connection is dubious at best.
The actress, Clara Bow, usually called "The It Girl", was sometimes nicknamed �The Bee' - a reference to the initial letter of her surname - and she had a beautiful pair of legs, which she took full advantage of in her starring roles. It is claimed by some that the phrase �the bee's knees' was an acknowledgement of her perfect limbs. That is doubtful, too, as she appeared in her very first film in 1922 and her acting was so atrocious that all her scenes were cut! Presumably, Witwer's 1923 book mentioned above was already substantially written before Clara became famous, so that is another highly dubious source.