For anybody else confused by the fact that RAM is never expanded, I believe it's Random Access Machine [1]. At least, this is my conclusion after a cursory search for "oblivious RAM."
Yeah, it's a model of computation used in this line of research. See the original Goldreich/Ostrovsky paper for more info: http://dl.acm.org/citation.cfm?id=233553
Shortening Random Access Machine to RAM is standard in TCS.
Transdichotomous convex sets?
Theoretical Computer Science - at least that must be standard terminology among computer scientists?!?
I've only ever seen it spelled out "theoretical CS". There is GOFAI, though.