a few lead sheet questions

[Daniel Leidisch]

At the moment, I am using LilyPond to generate some jazz lead sheets,
which works fine, but there are a few minor problems I couldn't solve
myself:

- Is it somehow possible to have clef and key signature at the first
  staff only? If yes, how could I place barlines at the beginning of
  each staff (in order to “close” them)?

- What would be the most convenient way to have “section letters”?
  (Something like [A] at the upper left of the beginning staff of the
  a-section)
  
- How can I get a dash instead of “m” for minor chords?

I tried to search the (fine) documentation for these issues, but even
after quite some time I have not found a solution. Maybe I just used
the wrong keywords or there is not an easy way. Since I am still a
beginner, I find myself a bit overwhelmed with the docs sometimes...

TIA

dhl