e---------------------------|
B---------------------------|Riff 2
G---7--7/(9)-9--------------|
D---7--7/(9)-9--------------|
A---5--5/(7)-7--------------|
E---------------------------|
Parenthesis here mean that chord is optional for emphasis or whatever?

In this case it means slide from the 7/5 to the 9/7, but don't strum on beat 1 but beat 2.

Beat 1 - don't strum
Beat 2- don't strum
Beat 3 - Strum 7/5
Beat 4 - Strum 7/5 and slide to 9/7

Beat 1 - Don't strum, just let your 9/7 chord subtly ring out
Beat 2 - strum 9/7

etc

Get it?