The ecumenical Councils of Ephesus (431), of Constantinople II (553), and of Constantinople III (680-81) refer to the Blessed Virgin Mary as "aeiparthenos" which is Greek for "Ever-Virgin".
Dr. William Tighe recommends the following regarding the identity of the "brothers of Jesus":
John McHugh, The Mother of Jesus in the New Testament (1975).
McHugh considers all the alternatives, and comes down in favor of the view that the "brothers" were most likely foster-brothers.
Hat tip to William Tighe.