Export Joplin notes to markdown

When exporting notes or a notebook to markdown Joplin uses the title of the note for the created .md-files (and not the internal number). It would be useful if
a) the spaces in the name of the created markdown-files would be replaced by an underscore (e. g. instead of a note named “Joplin note” it should be “Joplin_note”).
b) Links between markdown notes won’t work when exporting from Joplin because they use the internal number. Is it possible to change this behavior?
c) Is it possible to implement the export of the metadata information too when exporting from Joplin (e. g. the tags, the internal number …)?
d) Is it possible to define a “merge / append” function to export several Joplin notes in one big markdown document? At the moment I use the freeware programm txtcollector for this to build a new markdown document from several Joplin notes. I know there will be also problems, when the notes are linked.