I don't have much time, but I took a closer look at the Andante of K 201.
There are some very interesting deep structures; I will try to provide some insights. Observing the first theme, it consists of a four-bar phrase. Observe the intervals (naturally starting from the upbeat before the bar): the sequence is 4 3 2 3 5. What do you notice? First of all, a contrapuntal relationship: the mirror inversion of the intervals at the extremes (4 and 5 are complementary intervals by inversion, the 2nd in the center acts as a pivot, the 3rd is the only part that remains intact).
Bar 5: modulating bridge. It starts from A4, descends to A3 in bar 7, and rises back to A4 in bar 8. How do we get there? Via an A major scale, regularly directed on the upbeat of bar 6, irregularly twisted in the descent of bar 6: this is the same framework as before (the first theme and the modulating bridge have the deep structure A4---A3---A4: the extremes are respectively the first thematic phrase and the last phrase of the bridge (motivic fragmentation three times over)).
Same thing, if you notice, the modulating bridge takes up the "French" thematic idea from the first bars (violin II). In the second phrase of the bridge, it takes up exactly the same idea with which the first phrase ends: another mirror.
The second theme derives from the first, why? Simple: observe the intervals and eliminate the extraneous notes, leaving only those of the chords. We have 3 3 and chromaticism. In the second half-phrase, we have B on the upbeat, C#, D, B, G#, E. Intervals: 2, 2, 3, 3, 3. Chromaticism and 2, 2 = conjunct degree.
To summarize: 3 3 conjunct degree conjunct degree 3 3 3... mirror.
I believe this relationship is reflected in the choice to move to D major at the end of the second theme; I don't have time now to delve deeper into it.
Now... the ball is in your court!