What's the difference among 'I leave tomorrow', 'I'm leaving tomorrow' , 'I'll leave tomorrow' and 'I'll be leaving tomorrow' ?

I heard people say, "I leave tomorrow'. Is it grammatically correct?

1. I leave tomorrow.
2. I'm leaving tomorrow.
3. I'll leave tomorrow.
4. I'll be leaving tomorrow.
5. I'm going to leave tomorrow.

All are correct. All have basically the same meaning. The differences are just slight differences in the conversational contexts where you would use them. These contexts are so subtle and numerous that it is impossible to explain each and every one within the scope of a forum post. Here's a rough sketch of the connotations of each, as I feel them:

1 treats leaving as an inevitable scheduled event.
2 treats it as a matter-of-fact event.
3 treats it almost as a response to certain conditions.
4 treats it as something to be imagined as it will be unfolding in time later.
5 treats it as a personal plan.

I take my final exam next week.
Fran meets her parents at the airport this coming Saturday night, so we can't see the movie then.

Kathy is singing in the school chorus tonight. Let's go and see the performance.
I'm having a party Friday. Would you like to come?

I'll call around 8 to check if there's anything you need.
In case of an emergency, Robert will notify the police.

Tomorrow night at this time I'll be attending a play at the New Theatre downtown.
I wish I could go on vacation with Lucy. Next week she'll be lying on the beach, relaxing, and enjoying the sun.

I'm going to plant a vegetable garden this coming spring.
Mike is going to take courses in economics next year.

no, it's just like saying, "He's the one that's going to take out the trash." The correct way to say it is,"He's the one who's going to take out the trash."

just say, "I'll be leaving tomorrow" that's it.
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Do you, a native speaker, say, "I leave tomorrow"?

I need a native speaker to confirm and give some opinions.


Note: the one who.. ; the one that ... these are relative clauses which are out of focus. The main focus is on Tense.
 CalifJim's reply was promoted to an answer.