Religion, politics, and gay marriage

Amendment 2 will be on Florida ballots this fall, defining marriage as the union between a man and a woman. Here's the ballot language:

Inasmuch as marriage is the legal union of only one man and one woman as husband and wife, no other legal union that is treated as marriage or the substantial equivalent thereof shall be valid or recognized.

The wording is vague in terms of it applicability. Does it mean that religious institutions cannot be forced to perform gay marriages? Probably not. That's already covered by the US Constitution's first amendment.

Does it mean that gay people in a long-term union don't get to enjoy the same protections as straights with regard to legal rights, such as health benefits and power of attorney? If so, how does that reconcile with the 14th amendment which guarantees everyone the same due process under the law?

And considering that the main argument of those who support such an amendment is the God-defined union of a man and woman being married, wouldn't that be a violation of the First Amendment's establishment clause? Shouldn't there be more of a reason than 'the Bible says so' for us to amend our state constitution? In a free society, why should atheists, agnostics, or Muslims be bound by laws based solely on a book they don't believe in?

Finally, the article I linked to quotes a guy as saying that children need a mom and a dad. I agree. But isn't a childhood with two loving adults better than a childhood with one loving adult? If kids need a mom and a dad, and that's the bottom line, should we prevent children from being brought up by, say, two brothers or two sisters willing to raise them?