Jeff,
You won't find much with your questions in DirectSOFT, your questions are better answered in the specific manaul for the CPU that you're targeting. All of the CPU manuals can be downloaded free from the AutomationDirect.com website.
Let me point you in the right direction concerning SPs, they are pre-defined, read-only contacts in the CPUs that are used for reporting status, errors and such. There are also some real handy ones for program control like SP0 (First Scan), SP1, (Always ON), etc..
The CPU manual details all of these for you.