mand, I read your post several times over the past few days and I just didn't know where to start.
I've seen several posts similar to yours and often a few days later the poster has worked out the problems themselves - by reading instructions and experimenting a bit.
Your questions are big and you seem to be following the wrong path the way you're trying to connect to iDS. Its not important to rush and connect to iDS, as you probably already have up-to-date software in your iLiad. We haven't had a big update for a long time and the last update was a little one to add Italian language support.
Connecting to iDS: Put aside your USB cable and your PC - you don't use them to connect to iDS. You don't need a MyiRex account to connect to iDS or PC Share.
Do you have a silver book edition iLiad or a black V2 iLiad? The book edition iLiad should be connected via an ethernet cable directly to a router to connect to iDS. The V2 has wifi, so if you have a wireless network available you don't need any cable to connect the V2 to iDS.
A whole separate issue is connecting your iLiad to your PC via PC Share. You can connect to your PC via ethernet cable to your router or wirelessly through your network, but you don't use the companion software or USB cable. This is where you use the iLiad Outbox in MyDocuments on your PC to send files to the iLiad and the share icon on your iLiad to send files to your PC.
iDS connection and PC Share connection are activated by long-pressing the @ Connect button on your iLiad.
You only use the companion software if you're connecting to your PC via the USB cable. Many people don't use the companion software (see my answer to your other thread).
Let us know how its all going and maybe someone else will jump in and try to help, too. Good luck!