i believe it is a hoverfly, 1 of 6000 possible species and yes to both of your questions.
the adult eats nectar and pollinate, the larvae consume lots of aphids.
they are commonly mistaken for bees or wasps.
the big kick is to get honeybees for pollination but there are so many plants that honeybees don't visit and the pollination falls on local/native bees and flies, like bumble bee, mason bee and hoverflies.