Thursday, March 27
0000 - 0999 is PA related infotypes
1000 - 1999 is OM/PD related infotypes
2000 - 2999 is Time Management
4000 - 4999 is Recruitment
5000 - 5999 is Erecruitment & E learning
9000 - 9999 is customer specific infotypes
To see a list of all OM related infotypes, you could use transaction code OOIT or table T778T.
On help.sap.com, they do offer a pretty extensive list and description on all of their infotypes. You could check it out @ http://help.sap.com/printdocu/core/Print46c/en/data/pdf/HRINF/HRINF.pdf
Tuesday, March 11
Before payroll could be run for an employee, the control record on this payroll area need to be released. This include if you are doing inhouse SAP Payroll or outsourcing payroll through an outside vendor, but utilizes SAP PCL cluster to track payroll run and extraction handle via PU12.
The payroll control record could be view via transaction code PA03 or via table T569V. On the payroll control record, it set the date retro date you can make modification to an employee that impact payroll and what payroll period you are currently in or going to be extracting for. When the payroll is in "released payroll" status, this mean it is ready for payroll extraction to occur for that payroll period. Once extraction is completed, the payroll is in exit payroll status to collect changes for next payroll period.
You could find out more about payroll through this really neat book I got recently.