#1
Found this fly in a grassland in Berkshire. The red thing is a mite that seems to be parasitising it. It keys out to Pallopteridae if you consider the vibrissae weak, though if considering them present, it keys to Piophilidae, either way I can't seem to fit this to a species in either family.
#4
Jan is right, a female of the genus
Geomyza [Opomyzidae].
Geomyza balachowskyi or
G. hackmani. The abdomen seems to be banded what points to
G. balachowskyi. However, the post scutellum seems to be rather dark what point to
G. hackmani. Unfortunately the colour differences are not totally reliable for identification. To be sure you would have to study sternite 8 (normally retracted).