This is another one a lot of people get wrong; the Commandment is actually, "Thou shalt not have any Gods before me." So basically, it's OK to be polytheistic, so long as you consider the Abrahamic God as the top tier; your Zeus or Odin, as it were.
Ignorance is the problem, not faith in and of itself. And that's a two-way street.
This one can be a bit confusing. Was not Yahweh part of a more extensive pantheon, with El as top banana? If so, would not El have been rather rightfully pissed that Yahweh was usurping its place in the hierarchy? Or is it possible, in Jewish mythology, that El gave Yahweh permission to form his own little cult of followers as some sort of cultural experiment?