I'd like to try to tackle your point 1, since I haven't seen people do that before. I should preface that I am indeed in favor of marriage equality, yet I think that it is incorrect to treat it as a human rights issue, or even an issue of equality before the law.
If you treat it as such, then marriage itself (or, rather, its sanctioning by the state, with all the attendant privileges for married people and corresponding burdens on the community) is an inherently discriminatory institution. Fiscal benefits? Extended insurance? Visitation rights? Why should these privileges be enjoyed solely by married people?
Countering that anyone who wants these benefits can get married is as obtuse as pointing out that homosexuals always had the right to marry someone of the opposite sex. If I am unmarried, why can't I name my cousin as a dependent for health insurance? Why can't I have my best friend immigrate to the US to be with me, instead of a spouse I don't have? What if I plan to be celibate all my life, but have strong platonic relationships? What if, instead, I am a polygamist?
It's quite obvious that, if these are indeed civil rights, let alone human rights, then any individual citizen should be able to enjoy them; and those that necessarily involve more than one person should be applicable to any pairing (or group?) of a citizen's choosing. Why should people who are not in a romantic relationship be treated as second-class citizens?
If, instead, they are not human rights or civil rights, but privileges granted by the state because there is a public interest in encouraging and supporting marriage, then the question of how far and to whom these privileges should extend is a perfectly legitimate matter of debate.
Even more so then, that the genders of the parties involved are completely irrelevant.
Eich might have defenses, but Philip's writing here is extremely weak.
1. A lot of people aren't viewing it as a "political" view like they would taxation or immigration. They see it as straightforward human rights. Just like we'd expect backlash against someone against "interracial" marriage. Even if we're saving those cross-race couples from expensive litigation!
2. He spoke about his views and got all cagey. If it was an accidental donation for a friend, he could simply admit so. Instead he refuses to elaborate. Perhaps he hates Prop8 and just wanted to see where this would end up. Or perhaps he is against all marriages in their current construct. If such things were true, then he could state his proper views and it'd be finished and mostly blown over.
3. It still might be an overall loss as civil rights will almost certainly end up in the right place. But it's not clear that an open web, for as much as Mozilla is fighting for that, will happen. I'd accept a hand from the most evil person in the world if my alternative was drowning.