First one, no.

Second one, yes.

For each node that contains children you will need to add the following code during population.

objTreeNode.JSFunction = "checkAllChildren(""" & objTreeNode.Key & """)"

Then in your js file you will need something lithe following.

function checkAllChildren(sId)
{
  var oTree = dnn.controls.controls['MyDNNTree'];
  var oTNode = oTree.selTreeNode;
  for (var i=0; i<oTNode.node.childNodeCount(); i++)
  {
    var oNewNode = new dnn.controls.DNNTreeNode(oTNode.node.childNodes(i));
    oTree.selectNode(oNewNode);
  } 
}
 
 

Note: A recursive call is not necessary, since the selection of a node that contains children will invoke its own function call.  Also note that I have hardcoded the name of my tree control in this script (MyDNNTree).  This is not adviseable for a real module, you will need to determine the name via the ClientID property on the server-side.

If you have any questions feel free to contact me.

edit: Sorry, I posted an answer to another thread here.   Changing now.

I am not sure I understand you question.   I am definitely not suggesting altering any existing js, rather including a forum specific js file (or including js in your ascx page, though the separate js file would be better since it could be cached).  

Note:  I may add something to the tree module in the future to make this easier.