No idea about the first 3 questions but I can kind of answer the fourth. I used to play at my School with a bunch of friends and it was really really fun, it wasn't competitive or anything. From playing MTG I made many good friends which I still have now. I would say if I were to play competitively I wouldn't find it that fun because I wasn't that great at it, but if you play it with friends it is really good, and so worth it.
I agree that it will be Half life 3. It could even be a combination of Half life episode 3 and Portal 2, as in, where their stories intertwine. Just speculation, because that would be one hell of a surprise.
They are currently beta testing a major CS:S overhaul, including achievements, domination/revenge, MVP and stats to name a few changes. They have being testing for a while now, but no date set for the release of the update. @topic: The latest news is that they canceled their Portal 2 showcase and have a "Surprise". My assumption is half life 3 which seems the most probable.
Look at GixG17. He is a very good roleplayer in the Elderscrolls games. I find Morrowind his best Let's Play because it is the first time he has played it, and it is funny to see the mistakes he makes sometimes. Also brings back good memories of how much fun I used to have playing Morrowind