850C network segration on 2+0 ACAP link

I am trying to setup and 2+0 Cross-polar link with 2 separate networks requiring segregation from each other but sharing the full capacity of the combined Radio Channels. Each network is to connected via fibre to an SFP port on 850C radios to each network’s own switches. These switches have been in service for sometime and currently only support 1Gbe SFP ports.

Reading through the User Guide I have a few queries regarding this setup.
Firstly, as per system release 12.5 (850C Overview, pages 853-855),port 3 (Eth2) is exclusively for dualband use (future release) and Port 5 (Eth 4) only supports 10G. Does this mean that Port 3(Eth2) is essentially unusable for general traffic? Does this mean that Port 5(Eth4) will not be able to be locked on to 1Gbe speeds or accept a 1Gbe SFP to connect to the older switches?

Secondly, if the physical connections can be established, does a LAG need to be setup combine each Ethernet service in order to push through the combined Radio channels? Also will this maintain the segregation of the networks or do further settings need to be used to prevent one network from being able to access the other?