Is it halachically permissible for an observant homosexual/lesbian couple to adopt a child and raise him or her as a Jew in accordance with Jewish tradition? As a follow-up question, is it halachically permissible for a Jewish school to refuse to admit the children of a homosexual/lesbian couple even though such school readily admits children of homes that are not Shabbat observant.

There are many questions in this teshuva: what is our response to homosexuals/lesbians, who is a Jew, what are the parameters required to be Shomer Shabbat in the modern world? But the true theme should be in responding to the "follow-up" question: in focusing on the individual; namely, the child who needs education to grow as a knowledgable Jew. We discuss the fine points of the status of gays and lesbians within the Jewish community. But in so doing, we too often lose sight of the individual. A Jew should not be defined by his or her sexuality, but rather by his affiliation as a Jew. Ezekiel is told by G-d that the proverb stating that the parent eats sour grapes and the child's teeth are set on edge should not be used "by Israel any more" (18:1-3) No human should be defined, rewarded or punished by the choices of the parent or life mate. Focusing on the parent as to whether they "can" or "should"  overlooks the fact that in our world, parents "do". And we, as a community, are responsible to raise generations of literate Jews.Upon birth, we are no longer ubar erech imo (literally: part of the thigh of the mother). We become individualized. And therefore responsible for our own selves. In recognition of that, we, as a Jewish community, are responsible to educate every Jew.

This is a very sensitive matter. As you know, the Torah law clearly prohibits homosexuality, so use of the term "observant" for  the couple is problematic. Adoption from a non-Jewish source requires conversion, for which the Rabbinic Court would want to make sure that the adopting family raises the child in full accord with Jewish tradition, so you can see the difficulty in this.

Insofar as school is concerned, it is difficult to justify schools turning down any Jewish child.

The Conservative Movement has a variety of t’shuvot / responsa on the question of the halakhic status homosexuality. These include papers by Rabbis Bradley Shavit Artson, Elliot Dorff, Joel Roth and Gordon Tucker. I would also recommend the book, Wrestling With God And Men by Rabbi Steven Greenberg, a gay, modern Orthodox rabbi. My position is based on the writings of Rabbi Dorff, a synopsis of whose views can be found in his book, Matters of Life and Death: A Jewish Approach to Modern Medical Ethics, pp. 139 – 151.