Lots of Questions About Tones

If I correctly gather which theories about tonogenesis are most widely- or well-
 -accepted; and if I understand them to the right degree; I don't understand
why any language has more than three tones.  To wit, a rising tone, a falling
tone, and a level tone: with no distinction between two different rises, nor
two different falls, nor two different level tones; and also, with no contour
tones.

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How do languages come to have more than one level tone?  And which ones
do?

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How do languages come to have more than one rising tone?  And which ones
do?

How do languages come to have more than one falling tone?  And which ones
do?

If three pitches (say High, Medium, and Low) are involved in the tone-system,
there are three possible rises; LM, MH, and LH.  Do any natlangs have all
three? If so, which natlangs?  If not, do any have both LM and LH? Which? Do
any have both MH and LH? Which? Do any have both LM and MH? Which?

Likewise for falls:  Which, if any natlangs, have both HM and ML? both HM and
HL? both ML and HL? Which, if any, have all three?

Do any natlangs have more than one rise and also more than one fall?

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How do natlangs come to have simple-contour tones, that is, peaks (rise-fall)
and dips (fall-rise)?

Do any have more than one peak?  Which?

Do any have more than one dip? Which?

How do natlangs come to have complex-contour tones, that is, peak-dips and
dip-peaks?

Do any have more than one peak-dip, or more than one dip-peak?  Which, if
any?

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Why would a tonal language with three or more pitches in its tone system, and
with both level tones and glide tones (rises and falls), need any contour tones?
Are there any such natlangs?  Which ones, and/or how many?  And what are
their tone systems like?

Why would a tonal language with three or more pitches in its tone system, and
with simple contour tones (peaks and dips), need any complex-contour tones,
or any glide-tones, or any level tones?
Are there any such natlangs?  Which ones, and/or how many?  And what are
their tone systems like?

Why would a tonal language with both level tones and glide tones need more
than three pitches in its tone system?
Are there any such natlangs?  Which ones, and/or how many?  And what are
their tone systems like?

Why would a tonal language with contour tones need more than three pitches
in its tone system?
Are there any such natlangs?  Which ones, and/or how many?  And what are
their tone systems like?

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Any information related to the above questions will be appreciated.

Thanks.

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