I would just make sure you're pressing buttons for a reason. It looked like some of those strikes were thrown out without considering the outcome. Also, if you block a wake up kick, don't let Kasumi press buttons. Her 9K isn't that good of a crush and her parry isn't scary. The rest is just learning juggles. Sarah has obscenely high stun launch damage and you need to capitalize on it. Don't throw away free damage. For Kasumi weight, I do these combos. They're likely not optimal, but they're fairly easy and do a ton of damage.
Stun KP 4H+K P/[6]P 4H+K 66H+K
Stun 1K P/[6]P 4H+K P/[6]P 4H+K 66H+K
Stun 3P+K 3PK 3PK 7K
Or if they don't seem to know the character, Stun 2P+KK 33H+K 33H+KKH P/[6]P 4H+K 66H+K.
You can't use 4H+K against walls, so just do whatever relaunch (3PK, 33H+K, etc) into 3KK, 7K, or FLA 6KK. Careful about using 33H+K against walls, though, 'cause it can knock them off axis and 'cause the rest of the combo to drop.
For extending stun, you can't go wrong with P, 6P, and 2P+K. 1H+KKH and FLA 1KKH are useful too.
EDIT: And more 3P+K. Sarah 3P+K is so good. Safe crush with good range. That launches on CH and very long stun on NH.