RSS is for Roland Sound Space.
Yes.
It's merely a definition that suggests how to get the best of your speakers by positioning them in a specific way.
No.
From Roland's website:
"RSS
For "Roland Sound Space," an effect that produces a three-dimensional audio image in which sound seems to be coming from the front, side, above or below the listener. "
Many of Roland's products having COSM-based effects processors feature the RSS effect.