Which SDK to download ? I’m given a choice of:

2015.3

2015.2

2015.1

2015 SDK, 

etc

    Is there any printed general overview about installing and using the SDK ?

   I’m going to need to write sales orders into Sage; any suggestions as to how to proceed would be greatly appreciated .

 (Sage: it would be a good idea to offer some direction on the /download/sdk/download page)