First, thanks for www.gnudb.org. There is a way to get the results sorted alphabetically? Because for the same artist, the various album names are mixed. So it is quite difficult to browse the same albums...
Also, there are plans to don't have results limited to get more than 50 occurences?
It is now possible to see all the results, it was a bug that limited the results. The results are now sorted on albums and on artists if you are searching for albums.
I've found the solution of my question 1 : the first page is "?page=0" and not "?page=1" but the first one is never accessible after using links to the next pages...