@chrcoluk Ok I already have an update on two of the issues.
I found this post on reddit.
https://www.reddit.com/r/PFSENSE/comments/e00han/no_wan_uptime_stat_on_dashboard/
It is correct in my case the /tmp/pppoe0up file was missing, so I manually cycled WAN from the interfaces screen and it appeared alongside with the uptime, as to why the file was missing dont know but its working now which is the main thing.
Another file also appeared which was previously missing which is the /tmp/pppoe0_ip file and I have observed now that using a gateway group for IPv4 no longer shows up the line with a blank gateway.
So the only issue left which is relatively minor is the ""/system_gateways.php: route_add_or_change: Invalid gateway dynamic and/or network interface" problem. The gateway IP been called dynamic is greyed out and automatically configured by pfSense itself.