"No union is more profound than marriage, for it embodies
the highest ideals of love, fidelity, devotion, sacrifice,
and family. In forming a marital union, two people become
something greater than once they were. As some of
the petitioners in these cases demonstrate, marriage
embodies a love that may endure even past death. It
would misunderstand these men and women to say they
disrespect the idea of marriage. Their plea is that they do
respect it, respect it so deeply that they seek to find its
fulfillment for themselves. Their hope is not to be condemned
to live in loneliness, excluded from one of civilization’s
oldest institutions. They ask for equal dignity in the
eyes of the law. The Constitution grants them that right."
Strictly speaking it means the laws against gay marriage were themselves illegal. (As with any law deemed unconstitutional.) It's a matter of word choice to say "gay marriage was always legal" versus "anti-gay marriage laws were always illegal". There's some semantic difference between the two, but I'm not sure what the difference is from a judicial standpoint.
That's basically correct. It's always been legal, and efforts to stop gay marriage have basically been efforts to narrow the scope of this already legal right.