Hello Vince,
NTreeListNodeSubItem is an abstract class. Depending of the data type that sub item holds sub item can be of several different types.
With some exceptions (NTreeListNodeImageSubItem, NTreeListNodeBooleanSubItem) all others types has property DisplayValue.
You can use this property to display the string representation of the subItem value.
NTreeListNodeNumericSubItem and NTreeListNodeDateTimeSubItem has also property called FormatString.
You can use this property to specify how to format your datetime or numeric value.
Regarding the second question, you can find the NTreeListNode that specific sub item belongs to its SubItems collection using Owner property.
You can get the name of this node from its Name property.
Of course the name of this node should be previously set, otherwise it will return null.
Best Regards,
Nevron Support Team