Toddler Troubles!!!

Sarah • 23 years old married with one three year old daughter and a newborn son
My daughter is 3 1/2, will be 4 in June. Her behavior has gone from bad, worse, terrible, horrific to just plain demon spawn! I'm very very worried about her. Here's a few horrid behavioral things she done in the last few days:
1: ran up and slapped my lower back so hard it bruised
2: took her juice bottle and started beating the cat
3: took a colored pencil and tried to stab to hamster 
4: she's choked the cat
5: punch her aunt in the face
6: spit on a cashier 
Etc etc...
The worst part is that she thinks it's funny and saying "I'm just playing momma" she thinks it's a joke! We try to talk with her and tell her it wring but no matter what we do for punishment it doesn't help. She's getting worse!!! We are having our second child soon and I fear she won't take it well at all. 
Does anyone have any advise on what I should do about her behavior? Does this sound normal for her age?