#1, Work Processes sandbox solution uses

Execution Manager: Loading and execution of sandboxed solution code
#2, Object model that subset proxy exposes:
SPSite constructor
SPSecurity object
SPWorkItem and SPWorkItemCollection objects
SPAlertCollection.Add method
SPAlertTemplateCollection.Add method
SPUserSolution and SPUserSolutionCollection objects
SPTransformUtilities object
Microsoft.SharePoint.Navigation namespace
■ All of the Microsoft.SharePoint.Utilities namespace, except
SPUtility.SendEmail method
SPUtility.GetNTFullNameandEmailFromLogin method
■ Microsoft.SharePoint.Workflow namespace
■ All of the Microsoft.SharePoint.WebPartPages namespace, except
SPWebPartManager object
SPWebPartConnection object
WebPartZone object
WebPartPage object
ToolPane object
ToolPart object
#3, CAML elements can be used in declarative solutions:
CustomAction
Field
ListInstance
ListTemplate
Module
PropertyBag
Receivers
WebTemplate
WorkflowActions
WorkflowAssociation
#4, List all blocked APIs in a farm:
foreach (SPWebService service in webServices)
{
foreach (SPObjectModelType type in service.RestrictedObjectModel.RestrictedTypes)
{
Console.WriteLine(type.FullName);
}
}