might they ... or not?

English as a Second Language English Vocabulary, Grammar and Idioms
1

Can one use:
[color=red]1-Might they arrest me or not?
instead of:
[color=blue]Is it possible that they may arrest me or is that impossible?
(In this case the answer cannot be: “No, they might not.”)

Can one use:
[color=red]2-Must they go out or not?
instead of:
[color=blue]Do they have to go out or don’t they?
(In this case, the answer to "2’ cannot be “No, they mustn’t.” but will have to be “No, they don’t have to.”)

2

The ‘or not’ tag sounds odd to me — redundant at least, ambiguous at most (‘Must they go out or must they not go out’??)