The tunes here earn their label: melodies that push past the comfortable top of the second octave, chromatic passages that lean on cross-fingerings and half-holing, or long-form pieces that demand real stamina and memory.
Approach them in sections. Loop the hard passage slowly until it is clean, then stitch it back into the tune — a habit that makes every level below this one feel easier too.
Range beyond the second octave B, frequent accidentals outside D major that need cross-fingering or half-holing, or sheer length and speed that demand strong breath control and memorisation.
Break it into phrases, practise each slowly until clean, and only then rebuild the tune at tempo. Slowing the play-along mode down is the fastest route to playing fast.
No — a good D whistle handles all of them. That said, tunes living at the very top of the range are kinder on a whistle with a sweet, stable second octave.