This one of your first and most basic resources. Available in various sizes from many different sources, but be sure to get the Hebrew-English edition. If your first language is not English, try to get an edition with Hebrew and your first language.
The following resources are useful to any non-Jew interested in Torah. Schueller House does not distribute them directly but points you to retailers.
JAMES WILLIAM PARKES
This essential historical resource covers the transition between the first followers of Ribi Yehoshua, who were Torah observant and respected within the Jewish community, to the development of a gentile "church" that followed a mythical figure antithetical to the church and became hostile to observant Judaism. The book was out of print but is now available from ACLS Humanities.
RABBI BENJAMIN BLECH
This was chosen by the Union of Orthodox Jewish Congregations as "the single best book on Judaism in our generation." A professor of Talmud at Yeshiva University, Rabbi Blech has also been lecturing around the world for years and has appeared on U.S. TV, including Oprah. Gateway to Judaism, The What, How, and Why of Jewish Life by Rabbi Mordechai Becher, if you've already purchased it, is an acceptable alternative for the khavruta.
RABBI ABRAHAM CHILL
"… the manner in which the Sages gave meaning and value to the mitzvot is the essence of the present volume by Rabbi Abraham Chill. He has culled from many basic biblical exegetes, rabbinic commentators and codifiers, mystic-kabbalistic authors and Responsa authorities. His work presents in digest form each and every perspective of every one of the 613 divine commandments and, in clear style and comprehension, makes the reader part of the whole gamut of thinking in Oral Law perception…" (from the foreword by Sidney B. Hoenig, Dean, Bernard Revel Graduate School, Yeshiva University)