Q: In the opening of Mozart’s Violin Concerto No. 4 (1st movement), would an ACO legend use a 1-2-4 or a 1-3-4 or some other fingering to keep the quavers in tune and make a good impression at an audition?
Opening 1-3-4 (maybe if it were D minor arpeggio I would do 124 but not for this.)
Q: The descending trill sequences (b. 98-99, b. 192-193) in Mozart’s Violin Concerto No. 4 (1st movement) … I’m having trouble deciding if they are supposed to be a trill with 3/4 repetitions or just a mordant?
Trills. I would try to do more than a mordant but 4 reps seems a lot to aim for.
Q: When practicing Mozart’s Violin Concerto No. 4 (1st movement), switching from 1st or 3rd position in bar 163 to 6th position within semi quavers is awkward and uncomfortable, does one overcome that with practice or with another technique (like Satu Vanska’s position scaffolding in the Souvenir de Florence excerpt on your YouTube channel)?
You should experiment with other fingerings and let the music decide what you should do – not necessarily what is most comfortable (but of course it has to sound good too!)