Fireside Soliloquy

With trumpets and fanfare.... My book C# Brain Teasers joins the Pragmatic Bookshelf's Brain Teasers collection in beta.  The running order of puzzles-which is subject to changes, since it's a beta-is below. In keeping with the format of the other books in the series, the puzzle titles are on the whimsical side, so Puzzle #0 is to try and figure out what the topics are: 1. All the Things 2. Advance With Caution 3. Nothing to See Here 4. What was the Year? 5. Unexpected Item in the Bagging Area 6. Precision Instruments 7. Inequality Among Equals 8. Double Jeopardy 9. So, What’s Left? 10. New Tricks 11. Property Development 12. Default Setting 13. Chicken or Egg? 14. The Optional Default 15. Deferred Judgement 16. A Promising Future 17. Fire and Forget 18. Exceptional Circumstances 19. Hanging Around 20. The Sentinel 21. A Narrowing Experience  I'll give a few clues: areas of C# that are covered include closures, async, primary constructors, user-defined operators, conversi