All though there’s no confirmed date, Microsoft confirms that keyboard and mouse support will be enabled on Xbox One in the coming weeks. With the new feature developers will be able to build mouse and keyboard support in their games. So basically its up to the developers to decide if they are enabling keyboard and mouse support on their game or not.
As for the connectivity both mouse and keyboard (Wired or Wireless) will be connect via USB port and looks like Microsoft is recommending Razor as best supported brand for the Xbox One. Which is a hint that we should also be prepared for some new mouse and keyboard product range by Razor just for the Xbox One. Microsoft also confirmed that Warhammer will be the first keyboard and mouse supported game for the devise.