I would suggest breaking this excerpt up into four different parts: A-m.1 to m. 4, B-m.5 to m.8, C-m.9 to m.12. Section A ends on a half cadence, section B ends on an Imperfect Authentic Cadence, and section C ends on a Perfect Authentic Cadence. It is difficult to put these into definitive sections because of the similarities of the rhythms for each section. They could be seen as parallel because of their rhythmic similarity and they all are the same length. Phrases A and B could be seen as parallel because A ends with a half cadence and B ends with an IAC and they both have similar thematic material. They could all be seen as contrasting because the harmonic rhythm changes to a slower chord change.
Mozart utilizes a lot of very interesting non-harmonic embellishing tones. These tones generally should be given more emphasis in performance situations like the upper neighbor e natural in measure 5. This is not expected because this excerpt of the piece is in f sharp minor and so we expect an e sharp. This gives the measure a semi-major feel. The chromatic passing tone a# in measure 8 should be emphasized because it is a resolution of a 4-3 suspension. A# is not in the key signature, so it needs to be more emphasized because of it's obvious majorness. The Neopolitans in measures 9 and 10 will get an emphasis in performance because it is not expected to play a bII and it is important to stress the oddity of this chord function. I think that any Ti Do movement or le sol movement should be emphasized because of its cadential importance. I think measure 8-10 would be a building up of tension because of the sudden move to a more major feel with the I and the N^6's. I think in performance, I would crescendo until measure 11 and then decrescendo to the end of the phrases.