1. I'm glad Eric is alive.
2. Seeing Eric meet Calleigh for the first time was ADORABLE!
3. The flashbacks were interesting, I think, and well played by the actors. It was clear how different Calleigh was then (smiling all the time, so bubbly and perky) and how she is now (more stoic and serious).
As for Adam Rodriguez and the fate of Eric/Calleigh, several articles @ CSI Files have revealed that:
-Adam will be in ten episodes this season
-His relationship with Calleigh will have a "resolution" before he leaves and that "people will be happy with the way it all ends"
-Eric's exit will involve him changing professions
-When he leaves, it's not for good. It's open-ended, so it allows for a cameo here and there (like Alexx, I guess)
According to Wikipedia, for episode 8.03: Three volleyball players mysteriously drop dead on the court while Calleigh's testimony against Delko threatens his future as a CSI.
This leads me to believe that they may have "irreconcilable differences" because of this mess with Eric's father, and that's why they break up. They'll probably remain friends, but I don't see how their romantic relationship could survive if he's not there.