Hmm, the window you described has a few sound samples in it, but generally I’d say the reversed stuff is a “reversed” (swelling in) impulse response, the warble is likely either modulated reverb time or the guitar whammy, and the washy stuff is the late reflections coupled with a low-pass filter.
EDIT: after looking at the specs, it also has a cabinet simulator, so that could be adding to the band-limited tape-filtery sound.
Sound On Sound always has great articles, and I found this near-exhaustive post on reverb in mixing that has like, waaaay too much info:
http://www.soundonsound.com/techniques/use-reverb-pro-1