I got convinced to use biblatex and already have the first problem.
I have several .bib-files and one of them contains only entries which shall be listed in a second bibliography (or even better: a subcategory of the bibliography). It shall look as shown here:
BIBLIOGRAPHY
entries from bib-files 1,2,3 alphabetically ordered
BIBLIOGRAPHY 2
entries from bib-file 3
The entries do not have any special types or keywords, I don't want to add them manually to categories and I don't want to split the bibliography by chapters/sections/segments/whatever.
labeloption as done here. If it should be sorted in the order of the source file (i.e.sorting=none), you'll have to use biber - bibtex can't cope with multiple sorting schemes. – Audrey Aug 10 '13 at 15:33