1- Is the ISDN Link connection to the LAN needed in this scenario as it will directly pair with the SX80?
If you're using it in an ISDN only scenario, then no, the ISDNLink does not need to be connected to the LAN. If you are doing ISDN as well as IP/SIP/H.323 calls, then yes, the ISDNLInk should be connected to the network.
2- I scenario 2, should ISDN Link LAN port be configured?
As above - it will depend on your installation scenario
3- What SX80 LAN port should I use for the ISDN LInk Pairing? Port 1 to LAN and Port 2 to ISDN Link?
LAN1 is for connecting the SX80 to your network. LAN2 and LAN3 are for the peripherals (ISDNLink/Touch10/Cameras/etc)
4- Confirm that all configuration of the ISDN link is done via the SX80.
In general, yes, the majority of the configuration can be done via the paired endpoint. There may be the odd instance where you may need LAN or serial connectivity to the ISDNLink for configuration or troubleshooting purposes.
Wayne
Please remember to mark helpful responses and to set your question as answered if appropriate.