1)The first three sentences are correct, of the second three sentences,
however, only the third, '佐藤さんは...教えてくれる' would be right,
if you would mean, Mr. Sato teaches him English for me or somebody else.
2)In case you would ask for favor, you could only express with 'もらえませんか',
for 'もらいませんか' can be used, when you will recommend someone else
so that something would get done for this person.
3) '~ていただく' is a polite form for '~てもらう', both of them are identical on the meaning.
4) You could have misread 'かもしれぬ' or something else with 'かもしれる', which is not
found in this form anyhow among the vocabulary in Japanese.
It is possible to write in kanji script 'かも知れぬ', but I take it advisable to write instead
in hiragana script 'かもしれぬ'.
.