Two questions about fingering indications

[Nick Payne]

I have the following code (it's the first couple of measures of Barrios'
prelude in C minor). Firstly, with the RH fingering, some of the indications
appear above the beam and some below, depending on where on the stave each
note is located. How can I get them to all be above the beam? Secondly, with
the LH fingering, I can only get the orientation to the left of the notehead
to stick by enclosing every note with a fingering indication inside chord
symbols, otherwise the fingering appears above the stems. How do I get the
fingering orientation to default to being to the left of the notehead for
notes that are not chorded?

Also, Lilypond puts a natural symbol against both b naturals in bar 2, when
only the first symbol is required.

\version "2.11.58"
% Treble voice
#(define RH rightHandFinger)
up = \relative c' {
        \set fingeringOrientations = #'(left)
        \set strokeFingerOrientations = #'(up)
        \set tupletSpannerDuration = #(ly:make-moment 1 4)
        \times 4/6 {
                \override Fingering #'staff-padding = #'()
                <c-1-\RH #1 >16 <g'-0-\RH #2 > <aes'-4-\RH #4 >-> <ees-3-\RH
#3 > <g-2-\RH #4 >-> <g,-0-\RH #2 >    c, g' aes'-> ees g-> g, |
                <b,!-1> <g'-0> <aes'-4>-> <d,-3> <g-2>-> <g,-0>    b,! g'
aes'-> d, g-> g, |
        }
}

% Bass voice
down = \relative c' {
        c4 c |          % 1
        b! b! |         % 2
}

\score {
        {
                \clef treble
                \key c \minor
                \time 2/4
                \tempo "Moderato"
                \override Staff.NoteCollision #'merge-differently-headed =
##t
                \context Staff << \new Voice { \voiceOne \up }
                        \new Voice { \voiceTwo \down } >>
        }
        \layout { }
        \midi { }
}

Nick