Hi Michael,
first of all a warm welcome to the AiE community :-)
I assume that you have an appropriate SAP AS ABAP in your company (maybe already 7.40?) you want to connect to with the Eclipse environment.
If you have access to SAP Service Marketplace (I think this was meant by SID) you can use the software download center for downloading the plug-ins. This content can be dropped into the plugins folder on your local Eclipse "installation". Service Marketplace is the primary distribution channel for SAP delivering AiE to the customers.
But the most convenient way to install ABAP in Eclipse is to use the mentioned update site https://tools.hana.ondemand.com/luna. But for this it's necessary to have access to the internet. You do not need a Service Marketplace user for just using it. The update site is available without any further authentication to make it available for everyone without being subscribed to a paid SAP license (otherwise a connection to a trial version would get even more complicated).
If you use it within your company's environment a Service Marketplace User is necessary for searching SAP notes and opening up support messages. But just for a simple use it's not necessary and you can even post questions and bugs here - like you have to do if you use it @home with the A4H trial (unfortunately you have to pay for it, but you can use even the older trial version with SAP Gateway, but this one is not available for download any more :-(
Did I cover your questions?
Best regards
Martin