Premise:
"At least seven more of the assassins surrounded them."
Hypothesis: The assassins formed a circle around them.

it is not possible to tell

Premise:
"Never got 'nother like him; he's special."
Hypothesis: He's one of a kind.

yes

Premise:
"Poirot locked the door on the inside, and proceeded to a minute inspection of the room. "
Hypothesis: The inspection by Poirot was a necessary evaluation.
it is not possible to tell