Hiya,
I seem to have lots of ants, on courgettes, outdoor cucumbers and chillis.
They dont seem to be causing any problems - in fact, the plants with ants seem to have less trouble in the way of aphids, also they may be helping with the pollen transfer on their little feet.
All plants are fruiting away quite happily.
In terms of your courgette flowers, they only seem to open first thing in the morning and then shut down for the rest of the day. I was worried that mine weren't opening as I only get to my plot in the evening, but was advised by a helpful soul on here of the morning opening and I am now up to my ears in courgettes!!