We use present simple when we talk about schedules, programs, etc. (for public transport, cinemas, etc.):
My train leaves at 11:30, so I need to be at the station by 11:15.
What time does the film begin this evening?
It's Wednesday tomorrow / Tomorrow is Wednesday.
You can use the present simple to talk about people if their plans are fixed like a schedule:
I start my new job on Monday.
What time do you finish your work tomorrow?
But the continuous is more usual for personal arrangements.
What time are you meeting Mohammad tomorrow (not do you meet)?
We use I am going to do something when we say what we have decided to do, but probably not arranged to do:
"Your shoes are dirty." "Yes, I know. I'm going to clean them." (I've decided to clean them, but I haven't arranged to clean them)
I've decided not to stay here any longer. Tomorrow I'm going to look for somewhere else to stay.
*Often the difference between using "I am doing" or "I am going to do" is very small, and either form is possible
About using will instead of going to, in general, we use will when we decide to do something at the time of speaking, but sometimes there is not much difference between them, such as the following examples:
I think the weather will be sunny tomorrow.
I think the weather is going to be sunny tomorrow.
There is no difference between these two, or at least, not much difference.
But in the following example, we have to use going to since we are making a statement based on the current situation:
Look at those black clouds in the sky. (I think) It's going to rain.
(Black clouds are often a certain sign of raining)
We can also use will when we are predicting the future:
Do you think Jill can pass the exam?
Yes, of course! She will pass it easily.
Here, we are not saying that Jill has decided to pass the exam, but we are saying what we think or know that will happen.
It is not related to this question, but it is worth mentioning that will can also be used about the current time. For example:
Don't call Ann now, Kate. She'll be busy.
It is my interpretation of why will has been used in the above example: To my way of thinking, Ann will be receiving the call in a few seconds from now, and not now; therefore, it is correct to use will instead of is.
I also found this usage of will in here (https://www.englishclub.com/grammar/verbs-m_future.htm)
The verb be is an exception with will. Even when we have a very firm plan, and we are not speaking spontaneously, we can use will with be. Look at these examples:
I will be in London tomorrow.
There will be 50 people at the party.
The meeting will be at 9.30 am.
At the end, I don't understand why "will stop" has been used here. In every aspect that I look at it, it should be "stop." However, it is surely intelligible.
Ref. (with slight modifications):
Units 19, 20, 22, and 23 of English Grammar in Use, Third Edition