ANSWER 1
He's isn't, as far as i know, grammatically correct. I believe the correct word to be used is his.
ANSWER 2
"He's" is an abbreviation of the two words "he" and "is."
Therefore, in a case where the two-word phrase "he is" can be used, so can "he's."
For example:
He is very tall = He's very tall.
What do you think he is doing? = What do you think he's doing?
However, it is NOT to be used as an abbreviation of "is he."
Example:
"Why is he embarrassed?" can not be abbreviated to "Why he's embarrassed?"
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A portable computer is very useful.
Have you read the transcript? It was very useful.
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The detective gained useful information by following the trajectory of the bullet.
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