If you put all the gay population in the world together, they could be the 4th largest Religion in the world. They are getting closer to that since they made Atheists a religion in the US.
This would be more dangerous for gays door knocking than if Atheists would do it.
I think there is a gay agenda. I don't know how it works politically - probably through pressure put on social institutions to promote their aims and discourage dissent. I'm not aware of any particular gay lobby that petitions at government level, maybe its done at local level.
I have never seen any gay activism tht endeavored to do more than redh a state of equality... for everyone.
Yes, there are national level lobbyign organizations. The best known would be the Gay and Lesbian Alliance Against Defamation (GLAAD). They played a major role in helping elected officials and the media realize in the 1980's that AIDS was not a gay specific disease, as a virus doesn't differentiate by a persons sexual orientation. The Reagan administration was deaf to GLAAD... until it actually started to affedt non-gay persons...
Yes, the Toronto gay parade is the largest in the world. They are even larger than the Xmass parade. That really changes some fairytales.