If your H265 material is HDR, vero will convert it to SDR for non-HDR screens. Results may vary as there is no standard way to do this.
No. TOSlink cannot do more than 5.1 (as DD/AC-3 or as DTS). Vero will extract core DTS from DTS-HD, or transcode 5.1 PCM to AC-3 if you tell it to.
This may help: