I save RAM previews to preview comps with real-time audio, since AE's RAM Preview lags on audio, preventing me from syncing video and audio. When I save the RAM preview, it starts slightly after where I have it set in AE and ends much earlier. How do I specify the RAM preview start/end parameters?
You can specify beginning and end of the duration to be previewed by setting a work area.
That doesn't necessarily seem relevant to your problem of lagging audio.
If audio and video are out of synch, then please file a bug with details about version numbers of software, kinds of footage, et cetera. You can send bug reports to aebugs <at> adobe <dot> com.