Sound normal to me.
He's a little young to get the whole baby in tummy thing, so don't chalk that up to sibling rivalry. He really doesn't understand what that means exactly, and only is asking b/c you have been talking about it constantly, and can see that your body is going through changes. You thinking he is upset with you over a baby sister shouldn't hold any weight. Still though, I would lay off the whole baby talk for a week or so. Instead, talk him up, fill him with positive reinforcement and let him know how he is such a big boy and you are going to be needing him to be your special helper soon.
For the grandparent thing, I don't even understand what the issue is with that. He probably had fun, and does miss them... why worry over that?
For the tantrum, it's all developmental. He is getting older and more independent and assertive. There are several techniques you can help with that.
For him being upset with you and telling you he doesn't like you, perhaps you have been emotional to him or others, and your behavior has changed and he picks up on it. Children sense these things and being pregnant, by your own admittance, causes hormones to make us extra sensitive, as well as makes us have a more difficult time moving around, standing, breathing, being extra tired.... I agree, it would hurt my feelings as well, but remember that he really does love and cherish you, just maybe doesn't have the best communication on explaining why he is upset or angry. Even though it is out of character for him, kids, like adults have their off moments. There are techniques to help children who are going through 'angry' episodes that can help.
Okay, so here is the discipline techniques... scroll down to the 'Bothersome behavior' section and it specifically addresses tantrums/hitting.
http://www.askdrsears.com/html/6/T060100.asp
Here is a section about helping a child handle their anger:
http://www.askdrsears.com/html/6/T061700.asp