metronome mark position

[Libero Mureddu]

Hi,
I'm trying to play a bit with the metronome mark and the \mark \markup
commands in order to have a unified way to set the tempo in my scores,
but I'm a bit lost:
the three rules I know for that are:
1) if there's a time signature, the tempo should be left aligned with it,
2) if there's a long key signature, the tempo should be aligned in the
middle of it,
3) if there's no time/key signature, but just a tempo change (as in
"più mosso" etc), the tempo should be aligned with the leftmost note
of the bar.

In the following snippet 1) and 2) seems to be possible only using
\mark \markup, while 3) is the default behavior of \tempo.
However, in 1) the "A" of "Allegro" is aligned with the center of the
time signature, not left-aligned.

I have two questions:

Is there a way to have the \tempo or a custom \mark \markup that
behaves correctly according to those three different situations?

In the example, there are two commented lines that should (in my
understanding), move the metronomemark on the left, but I only get to
have it down. Is there a bug, or am I doing something wrong?
Thanks a lot.
Ciao
Libero

%%%Example about tempo markings
\version "2.11.50"
\relative c''{
        \time 4/4
        \override Score.RehearsalMark #'self-alignment-X = #-1
        \override Score.RehearsalMark #'break-align-symbols = #'(time-signature)
\key c \major
\mark \markup{Allegro }
c c c c
\key cis \major
\override Score.RehearsalMark #'self-alignment-X = #-1
        \override Score.RehearsalMark #'break-align-symbols = #'(key-signature)
\mark \markup{Andante }
bis bis bis bis
%\override Score.MetronomeMark #'side-axis = #X
%\override Score.MetronomeMark #'direction = #-1
\tempo "Più mosso"  c c c c
}
\layout{ ragged-right = ##t }
%%% end of example