Hard talk refers to dealing with unpleasant subjects in a truthful way, no matter how much people, or more likely a group of people, may disagree. For example, if my city had a major corruption scandal that the politicians did not want to talk about, having a TV or radio show in which they were specifically asked questions about the scandal and its details would be 'hard talk'. Second - 'fast asleep', meaning in a deep sleep, is correct. 'Fast sleeping' is awkward and even if it was used, would mean falling asleep quickly. You would almost never hear it.

'argument-like' - better is: 'argumentative' or sometimes 'confrontational'. Perhaps 'controversial', 'frank'. 'Straight talk' has a similar connotation, as does 'Hard-ball', the title of television talk show here. It's a baseball reference. 'Soft-ball' is a variation of baseball that uses a larger, softer (slightly, if at all) ball and slower, underhand pitches. 'To play hard-ball' is an American idiom that means to act aggressively in some way or another. If you watch Hollywood action movies, eventually you'll probably hear the phrase 'all-right now it's time to start playing hard-ball'. It means roughly, 'to put on the boxing-gloves'.

"Fast sleeping" sounds awkward to me also. It doesn't really mean anything to me.

Well, to me 'fast asleep' also has the implication of falling asleep very quickly. ex. "I had never worked so hard in my life so when I came home I fell fast asleep."