Last update for the week end : I installed classicwb, and even if some of the features I wanted are already installed (dOpus, whdload), other ones are really difficult (for a lame amigan like me) to disable.
Some other tweak I'd like to add are impossible to do because they cause conflicts (as far as I understand) with the tweaks already installed too.
So finally, maybe creating my "perfect wb" from a BetterWB installation will be easier.
I'll keep you informed of the next (fascinating) episode of my AMigaOS reborn.
EDIT : by the way, in BetterWB Dopus-like program, when I want to unarc a LHA archive, there is an error saying something like "error Lz L command unknow". So I went into prefs and changed it to "lha x". THen, it worked. I don't know if it's a bug or not.