I was of the impression that whenever a word ends i “u” or for example “ru”, then it’s a verb (of course this is not always the case, but I am quite sure it is here). “To be sold out” would be more of an adjective and would therefore end in な or い (also according to the Memrise grammar lesson).
So if we’re talking about a verb and the adjective is “to be sold out” would the correct translation not be “Selling out (depletion)”? I think there is quite a significant difference between the two.
The male speaker just says “助ける”, which I suppose is a mistake. If i recall correctly, at least one of the locals also only say “助ける” when the word is introduced.
As far as I know it’s a matter of consistency. The か particle at the end of a sentence can be taken to mean the sentence is a question, but for clarity and consistency they’ve been adding question marks. As far as I’m aware the addition of the question mark is also becoming more common in Japan, but it is not strictly necessary.
Perhaps the question mark and the exclamation mark should be in same order? It’s possible to get the question wrong if you put them in the wrong order.