will, going to, 'll

[Rolin]

How to use them properly?

[Casiopea]

ex: I am going to be a doctor. <I have put some thought into it>
ex: I will be a doctor. <I know it; it's a fact>
ex: I'll be a doctor. <I'll is a contraction of I will>

Contraction
I will => I'll (the apostrophe (') replaces the letters <wi>)

[hochengcheng]

will - Will you come tomorrow night? (unplanned situation)
going to - It's going to rain. (predicted situation)
'll - I'll see. (informal way of expressing 'will')

[Casiopea]

Welcome, hochengcheng.

I, too, have a question. How do these differ?

[1] Will you come tonight?
[2] Are you going to come tonight?

All the best.

[Rolin]

a teacher of mine told me that 'll was used for instant decisions and that using willl in those cases was wrong.
Eg: Jane:you are an estupid
John :stop saying that or i'll kill you.( using will there is correct?)