SP 20 is the current release and SP 21 is supposed to be available toward the end of this month. SAP tries to release them about quarterly. It used to be that SAP would show the links for downloading a couple of versions prior to the current one, but they've added a new download site that no longer has that available. Just know that if you're using an older SP, if you run into any issues, SAP will ask you to upgrade to the latest.

The information you're looking for might be available through here: https://wiki.scn.sap.com/wiki/display/BOBJ/Crystal+Reports%2C+Developer+for+Visual+Studio+Downloads. In particular, look at the "Supported Platforms" document.

-Dell