Circle Of Fifths Progression Analysis

How significant are circle-of-fifths progressions and minor chords and minor keys, in the two movements that you have studied? Throughout the 1st and 3rd movement of the Symphony, Mozart implements a circle-of-fifths chord progression on several occasions. The first instance of this in the first movement is from Bar 31 to Bar 34, where on the first two beats of every bar there is a descending pattern of diminished chord, and on the second two beats there is the circle-of-fifths pattern: A7 / D7 / G7 / C7. Bar 35 ends the progression with an F Major chord.
From Bars 139 - 145, we are given another circle-of-fifths progression. This progression interchanges in tonality - a minor 7th chord, followed by a major 7th chord, and so on. Every half of a bar is a falling two beat-sequence; however each sequence fits into the tetrads. From Bar 143, the progressions become more frequent (two a bar). From Bars 148 - 153, we are given another circle-of-fifths progression - however, this progression is not based on chords, but on the key. Each key (with the exception of the first) spans two bars, yet irregularly - the modulations are implemented in the middle of the bars (the third beat).
The final circle-of-fifths progression in the movement is used in Bars 172 - 177.
Every two bars follow the pattern of:
a) Major 7th chord in the 3rd inversion
b) Major triad in the first beat, minor in the second, diminished in the fourth; all in first inversion; the bass note is absent on the third
beat

In the third movement, we are given just one progression - from Bars 76 - 81. The progression goes from B7 Major to C Major, and every two bars follow the pattern of:
a) Major 7th Chord
b) Major Triad

Though the key of the symphony is C Major (each movement starting and ending on), there are modulations throughout, and minor keys are a significant part of these modulations.
In Bar 81 of the first movement, as well as the dynamics marked as forte, the shock value of the chord is the fact that it is in the tonic minor - the exact opposite of what the listener would have been expecting after a dominant 7th chord (marked piano). This tonic minor chord continues until Bar 87, where it is replaced by a dominant major chord in the second inversion (however, this major chord would be normal within the harmonic minor scale).
In Bar 169, we are given an E7 Major chord. Previously, there had been two two bars sequences of C Major and D Major, but this sequence is different - the woodwinds play a descending A harmonic minor scale which prepares us for the dramatic A Minor chord.
In Bar 68 of the third movement (the trio section), we move key from the tonic major to the relative minor (A Minor - although the first chord is Chord V - E Major). By the end, after the circle-of-fifths progression, we move back into a major key.