Terrible two already?!

Katie is 22 months old. She pushed her cousin Ember last week. Since then she has pushed my friend's little boy down and made him cry and pushed our neighbor's little boy. Her Dad secretly finds this funny. It is mortifying to me however. My sweet little girl... I am struggling to know what to do with her and I am frustrated as she has begun whining a lot more, saying no, pulling on me to go the opposite direction that I want her to go. I have swatted her behind (she didn't care. She had plenty of padding and didn't bat an eye.) but I don't really like doing that. I put her in time out and she thinks it is a game. Karina said that she is probably acting out to get attention because of JD. (She had been doing so well at first. I guess she finally figured out he was here to stay.) So I have been doing a lot of reading about it and now am trying to process it. First someone said, "Behavior is neither good nor bad. It is exploration." Interesting way to think about it. Here are some suggestions that I have been reading about.
1. Distraction
2. Whisper
3. Use your "VOICE OF GOD" when they're in danger.
4. Load them up with positive reinforcement and attention when they're doing something good.
5. Say "it is not ok to ... Let's... instead"
6. Prevention.
7. Play with them to get them to do what you want. Make it fun.
8. Make sure they are well-rested and well-fed.
(The last two days have been worse than others and she missed her naps both days. Not that I didn't try to get her down, she just wasn't having it.) Finally today I had a plan of attack: take her outside right after breakfast and wear her out! It worked. (Thank God.) She has been out for over 2 hours.

I've been working on #4 but I can always do better.

Any other suggestions out there?