#1 and #2 are functionally identical in the modern Logix driver.
#3 is always helpful.
#4 is usually helpful. If you do this, you do not need to mess with “Communications time slice” setting. Note, the latest L8x processors have a dedicated comms processor for their front ethernet port, mitigating the problem separately.
#5 You can still read/write AOIs for light duty items, like leased tags for configuration UIs.
#6 What? (Prime number poll rates is utterly useless in Ignition. I don’t understand where you’d apply it in the PLC itself.)
Items to also consider:
#7a: Never, ever, ever access aliases. Always directly read from the corresponding base tag.
#7b: Consolidate scattered tag instances into arrays or nest them in structures. The fundamental unit of optimization when polling is the tag. Multiple items won’t be in consecutive memory locations, and therefore be retrievable together, unless they are part of the same tag. If you must, you can use aliases in the PLC to retain the prior logical structure, but access from Ignition via the consolidated tag(s).
#8: Never poll across a WAN. Latency crushes polling protocols. Place your OPC/UA server local to the PLC and let OPC deliver updates across the WAN. (Or use MQTT to deliver across the WAN.)