I have some rust around the freehub axis, should this be treated and how? After removing the wheel, I found that there is some rust at the place where the quick release axis would normally go through. It is not an old bicycle but heavily used in all weather for commuting. The wheel mechanisms operate well so far. How serious is the rust near the axis openings of the freewheel and does it need any treatment?

It's not the end of the world but I'd take steps to remedy and prevent it.

Clean the rust off as best you can with a wire brush or steel wool.
Coat the axle end and the quick release skewer with a light layer of grease. Something that resists water will help.
I'd also try to get a little grease down inside the axle. Nothing crazy, a light coat will work.

All-weather riding is a challenge for bicycles. Most new bikes are not assembled with all-weather riding in mind. Inspect the rest of your bike for rust or needed lubrication. It would be best to set an inspection schedule for your bike.