Hi there,
I think it's perfectly normal to have WirelessRadioManagerd running. It is a new process that Apple added in El Cap. I don't believe that File Sharing or Screen Sharing come turned on by default. Perhaps if you turned them on on a previous mac you had, they might remain on when you transfer your account and settings to your new Mac, but I believe they are off by default (maybe someone can confirm this for you). If you find that file sharing and screen sharing are both turned on, you might be the victim of an attack, like I was.
For me, I found my computer was acting slowly one day, so I opened up Console, and saw that the screen-sharing process was repeatedly running (you'll have to forgive me, I forget the name of the process), but it was appearing a lot. After consulting the Google I deduced that someone was trying to brute-force figure out my screen sharing password via the web. My computer was accessible to the web, not hidden behind a router or firewall, which would have probably blocked the login attempts.
Anyway, if you don't need those services and you are not sure how secure your internet connection is, I would turn them off and make sure they stay off. If they don't stay off, you might have a problem.
But that's just my informed opinion.
