XO Forum is closed here, migrated to https://xcp-ng.org/forum in the Xen Orchestra section.
To give you quick answers:
- 2 networks in general is fine (web+management, and remote data share for the rest)
- CR isn't using a remote, it's streaming from a host to another one, passing through XO in the middle. There's a backup pressure, meaning the stream is going at the speed of the slowest element in the chain.
Don't try to dig a lot: the speed you have is normal and due to how XS/XCP is exporting VHDs.