1. The only extant rules are in XTRO Primitives Vol. II. Any disclosure decisions regarding Interstellar Ops are beyond my pay grade.
2. Remember that "Early Spaceflight" refers to a period of time up from 1950 to 2200. The first ASF was the Chimera (per XTRO Primitives Vol. I page 14) and was introduced an unspecified period of time after 2297 but some time before the SB-26 Sabre was introduced in 2314. Either way, even allowing wiggle room, their availability is probably not part of the 1950-2200 ES era.
3: That has not yet been identified.