It sure does but the odds of me using it are almost zero since I keep it docked and play on a big TV. Maybe Professor Layton will get me to pull it out but I imagine the puzzles will still be designed around the fact that a lot of people will not be using the touch screen. It's going to affect the types of puzzles seen.
Not really, they're all self-contained. That said you should play Professor Layton and the Curious Village, it's quite good and has a high quality remaster on mobile phones.