SCSM 2012 allow you to communicate by SDK. SDK is supported way to get data from SCSM 2012. All other methods (SQL queries and IDataItem interface) are not supported by Microsoft.
Most of workflows that running inside of SCSM 2012 use WF (Workflow Foundation) so you can create your custom workflow easily. NOTE: Custom workflow must be target to .NET Framework 3.5. NOTE: You should always try to use only the SDK methods with your custom workflow.
SCSM 2012 use WPF (Windows Presentation Foundation) for all UI elements. With SCSM 2012 you can extend UI by creating custom elements like:
The most common problem with UI components is what UI use the IDataItem interface and DataAdapters classes to communicate with SDK. So you can't use SDK in forms and console tasks directly.