I think that a comma is mandatory after address, thus the two respective sentences would turn to be:
Children, who is going to come to the cinema tomorrow?
which is a question about future happening/events, but also about past decisions (who are the children who have already decided/planned to come). The latter is related to using "going to" for planned activities.
Children, who will come to the cinema tomorrow?
This is more about children's will/intent to come.
The Song of Taliesin: Tales from King Arthur's Bard - Page 71 John
Matthews - 2001
"Who will come with me to fetch this thing?" Because I was among
those who said they would go, I am able to tell this story.
Boys' Book of Frontier Fighters- Page 39 Edwin Legrand Sabin - 1919
"Who will go with me to rescue Burr Harrison?" he thundered. The
voices of the women were stilled; the men hesitated, looking one upon
another. The Indians evidently were waiting for just such a try.
See this forum discussion and this one.
You may want to see this famous grammar on the matter:
A Modern English Grammar on Historical Principles: Volume 4. Syntax (third ...
By Otto Jespersen
It excels on historical examples and considerations.
Also, perhaps the best contemporary presentation of English tenses:
The Grammar of the English Tense System: A Comprehensive Analysis, Volume 1
By Renaat Declerck, Susan Reed, Bert Cappelle
The links send you to relevant pages in each reference.