We don’t plan to release these publicly.
Well IR can be impacted by the environment. There is an external receiver included if you wish to hide the device behind the TV or in a cabinet.
The IR receiver can be used to record custom remote profiles via irrecord. There are a number of presets available under My OSMC → Remotes.
The RF dongle is only used for the official (included) remote. You can also pair a remote via Bluetooth too.
No. The Ethernet has to PHYs (internal and external) which are muxed together. The external PHY is used for RGMII.