roman sexual practices (without getting graphic...)

[Quintius Clavus]

There is Roman Homosexuality by Craig Williams, 1999. One of the first things he stresses is that the ancients did not divide sexuality along the same binary we do. They had no words for either homo- or heterosexuality and looked more at role rather than with whom-not to say that it was the only criteria for Romans. His goal is to try to get at how the Romans understood and experienced same-sex relationships, which is complex, as well as discussing the Roman understanding of Masculinity.
Within The Marriage of Roman Soldiers by Sara Elise Phang, 2001, there are two chapters - 8 and 9 - which deal with the short-term sexual relationships of Roman soldiers. Chapter 8 idiscusses their relationships with women and Chapter 9 discusses the evidence for those with boys or men (and there is some). In Chapter 8, she also discusses a little of the Roman view of what constituted rape.
I have a copy of Roman Sex, which I picked up at the Metropolitan Museum of Art. It is well worth reading, with many photos or drawings of artifacts, and again seeks to get at Roman attitudes including away from Rome itself, in the provinces-such as Roman Gaul.