If you want to sell your mobile app in Microsoft's Marketplace, then yes. They charge the same as Apple does in the iOS App Store.
If you want to sell your desktop app in Microsoft's Marketplace, then yes. They'll charge the same as Apple does in the Mac App Store.
If you want to sell a desktop app outside of Microsoft's Marketplace, then no, that's free. Just like it is on the Mac.
If you want to sell your mobile app in Microsoft's Marketplace, then yes. They charge the same as Apple does in the iOS App Store.
If you want to sell your desktop app in Microsoft's Marketplace, then yes. They'll charge the same as Apple does in the Mac App Store.
If you want to sell a desktop app outside of Microsoft's Marketplace, then no, that's free. Just like it is on the Mac.