Is it possible to decrease the size of the font that appears in the breadcrumbs?
You can change the width of the various components but not the font it seems. I think this is an oversight as other toolbar elements, such as the filter box and the content-type drop down, use whatever font is assigned to the toolbar via Customize.
I'll file a bug report suggesting that the breadcrumb field should also use the toolbar's font.
Can you add arguments about breadcrumbs pathfield in FAQ please... i don't find them in manual.
There're in the Release Notes. There are also some examples in my Opus 9 guide.