T.G.
I have a 4 year old that enjoys lying as well. He's quite good at it, too! I've just recently discovered what will work for him. When he's telling me something that sounds a little fishy, I'll pry a little more. I'll ask him, "Blayne, is that the truth? Is that REALLY what happened? You know, I LOVE it when you tell me stories, but I really need to know that it's a story so that I can enjoy it. Can you please tell me if this is the TRUTH or a STORY?" And he usually insists that it's the truth the first time. I'll let him know that he won't get in trouble for lying to me IF he tells me that he's telling a story, but I find out that what he's telling me is NOT the truth, then there will be consequences (always leave them unnamed, because a 4 year-old's imagination works a lot better than yours and they can come up with worse punishment than what you do. Besides, it might be worth time-out for him to go across the street by himself). For me, after a week or two of doing this, he started volunteering what was a story and what was the truth. Of course, after he tells you that this big long elaborate story was not the truth, you HAVE to reward him. Don't punish him for telling you that he's lied because that will encourage him to lie to you longer next time. Each time that you reward him for telling the truth, he'll be more likely to tell the truth earlier the next time. Before too long, he'll come up to you and say, "I wish Daddy were home so I could help him in the yard." instead of "Daddy needs my help in the yard today."
As far as the babysitter goes, try getting an older one that can recognize the escalation patterns of children. Most teenagers look at children as equals and that's why they play together so well. If a college student babysits for you, she'll be more likely to know what to do when your child STARTS to get angry instead of waiting for him to kick her.
And spitting is normal at this age. The best thing I did was teach Blayne about germs. Sounds odd, I know. However, when he realized just how many germs were in the mouth, the importance of covering your mouth when you sneeze and cough, and how spitting was rude and spread germs that could make others sick, he stopped spitting. I also taught him other ways to express his anger. I told him that it's okay to tell someone that they are making you mad and you want them to share their toy. It's also okay to put yourself in timeout until you figure out a way to get your way. He doesn't do that too often, but it does help when he thinks about what he's doing before he acts.