1)
Who are "ha'Shomerim Havlei Shav"?
1.
Rashi: They hope for salvation via idolatry.
2.
Malbim: They trust in people. Their promises are empty and vain, like it was with Anshei Ke'ilah. I trusted in Hashem!
2)
What was the consequence of David's hatred for them?
1.
Radak: When he fled Sha'ul, he did not ask diviners or astrologers about his wanderings. I trusted only in Hashem. "El Hashem" is like Al Hashem. 'El' is used with expressions of Bitachon, e.g. "Betach El Hashem b'Chol Libecha" (Mishlei 3:5).