If one of my kids ever hit or kicked me....
OOOOOOOOOOOH....the first time would be the very last time. He may have anger issues, he may be jealous of the baby, frankly, it doesn't really matter. If he can control himself at school and in other situations, he can control himself at home. Period. If my kids even tried getting lippy with me, I'd say, "Excuse me! What is rule #1?" They both knew it. It's RESPECT YOUR MOTHER. If they ever hit or kicked me, with one look, you can bet they'd have been on their knees begging me to spare their life. I never whipped my children. I didn't have to. They knew when I was pissed and when they'd pushed too far. A time out? Pfffft. Taking some toys away? Pfffft. That's what you do when they throw a fit over not getting a second cupcake. Hitting or kicking mom? That's solitary confinement. He should be grounded...big time. Allowed out of his room to go to school, to eat, to bathe and brush his teeth and go right back into his room. No friends, no TV, no toys. One week. If he apologized to you, accept his apology and talk about why he is being punished, but DO NOT GIVE IN. No "he said he's sorry so one day in his room is enough." No way. He needs to know you are serious and will follow through and he needs to know if he hits you or kicks you again, it will be 2 weeks next time.
Don't cave in and feel sorry for him. He needs to realize the consequences for his actions and that won't happen if you don't make the consequences something that will sink in.
If you could ask my kids, do you know what they would tell you rule #2 is? It's THINK before you DO. In other words, "If I do this, will I get in big trouble? If the answer is yes, I better not do it."
Like I said, your son already knows not to do those things to other people. You can work on finding out why he's angry or other ways for him to deal with it, but in the meantime, punishment should be swift....no questions asked, no negotiating, no backing down.
The bigger he gets, the more he will be capable of seriously physically hurting you and you need to stop it now before it gets to that point.