1) Is it preferable for mesh portals to be on the same channel or different channels?
A: This depends on the use case. If the design depends on maximizing capacity, it is preferable to have portals on different channels with different cluster IDs. They can collapse back to a common shared failover portal as the lowest priority cluster.
Also, this can be done if the scenario is that backhauling of video traffic is being performed.
Where, it is preferable to run certain cameras to portal A, others to portal B.
If shared bandwidth is OK for the application typre that is used – typical of most port/rail/transportation/manufacturing meshes – then they can be on the same channel and same cluster ID.
2) Is this a choice b/w faster failover (same channel) and faster throughput (different channels)?
No. Failover time would be comparable in both cases. Generally, a bit longer in multichannel case.
Since AOS mesh by definition is single-channel backhaul, the reason to have multiple portals on different channels is if we are explicitly trying to increase the overall system capacity.
3) Is there a preference for running ARM on mesh radio?
ARM is not preferred on outdoor mesh setup's.