These really seem like two different questions and that may just be because we don't know much about the pathogenicity of Reston virus - a live Reston virus may be more pathogenic than we tend to think. It also seems like cross-neutralization doesn't happen much with the ebolaviruses - see the linked paper. It might provide some great additions to a mix of candidate antigens, though.
The immune response including neutralizing Abs in humans and animal that survive EVD tends to provide strain-specific protection.
Since Reston is essentially not a pathogenic virus for humans; natural course of such infections and its impact in protection against other pathogenic Ebola viral strains in humans will be difficult to gauge.
Animals that survive following experimental Ebola Zaire virus infection do not exhibit protection from subsequent challenge with Ebola Sudan virus