small ternary (or possibly, small binary); no, the small ternary is truncated: a contrasting middle beginning at m. 45, leading to a premature dominant arrival at m. 48. (The theme could also be seen as an incomplete small binary, especially considering that the second part begins with a motivic reference to the first part.)
modulating sentence (presentation + continuation)
the melody and accompaniment texture along with the triplet sixteenth-note accompaniment provide continuity from the interior theme into the refrain