On your points…

1. I believe in freedom of speech. But sometimes people make statements just to get a reaction out of other people.
2. I also agree with your second point. In fact, for me that flag has become a symbol of Marxism and neoliberalism, both of which are ideologies I strongly oppose. The rainbow flag is more of a red flag whenever I see it.
3. I agree that teachers should keep their work lives and personal lives separate, and should not promote their orientations, whether they be hetero, homo or bi. I’m all for telling primary school-aged children that some kids have two dads or two mams, and that sometimes two adults of the same sex live together or get married, but that’s as far as it should go. And to be honest, most kids don’t care. I didn’t care about homosexuality until I was 14, when it started to affect me personally, but between the ages of 10 and 14 when I was familiar with it and seen it on the telly I didn’t care about it at all.
4. GC people can their be for, against or indifferent towards gay rights. Personally, I don’t know any GC people in real life besides myself, my dad and my best friend, and all three of them support gay rights. But the enemy of your enemy is not always your friend, and there are some GC people who think that homosexuality is wrong.
5. I did just that on my iPad. Whenever I typed "pride flag" the trans flag came up. Apple needs to get their shit together.