I THINK your version also should be acceptable, unless your original sentence had something else in it that DL didn't like. But if you get this exercise again and "kdo na mne čeká" is rejected, you might want to use the Report button. It may be an overlooked alternative.
There is the word "chci" among English words in the word bank. Not among the hints :-).
These words are not hints. Hints are the translations that appear when you hover over the words of the sentence you should translate. You may think I am just insisting on unimportant words, but I am not. When people report there is something wrong with "hints" we must know what hints are.
So the words you see are not hints, they are the words in the word bank. We do not control these in any way. Duolingo just chooses some words automatically and to some extent randomly. It is not worth to report these. Certainly not to us.
The pronunciation of "mě" and "mně" in Czech is identical, you always have to make the little "n" sound before the "ě".
Actually, mixing up "mě" and "mně" in written language is one of the most common mistakes Czechs do, exactly because of this - the sound is indistinguishable and you have to remember which one goes where.
It's interesting that Czech mě is pronounced like Russian "мне" (mně), but Czech mne is pronounced differently
It is because Czech E corresponds to Russian Э.
Russian Е corresponds to Czech JE.
waiting on is an acceptable translation. It means basically the same as waiting for.