In response to your first question about the melodies, regarding why F is the most important note in the first bar:
- It is the first note, and appears on every beat of the bar.
- It's the most commonly occuring note, appears 5 times as opposed to one G and two Es.
- It's in the centre of the range of that bar.
- There is an ornament on F, second beat.
- You said to ignore harmony, so the fact it's the tonic doesn't apply.
After my exam tomorrow I will be starting serious work on the rest of the exercises and should have something to show you soon
