Also, if the user wants to add an element to the hierarchy,

Suite and Optimus Suite 5
#1

Also,
if the user wants to add an element to the hierarchy, can I integrate with your
system to call up a DHTML dialog div to set up the details of that item
(multiple fields), have the record be saved via AJAX,
and then enter the item into the hierarchy on the fly?

#2

There is no ready to use sample for such features. But
they definitely can be implemented by using dhtmlxTree as base.