I started to answer this question with a reply to the comment but thought I'd just put a post together since this is should make it easier to find.

Question #3: Do you have the xsd file ?
There is an XSD for the navigator in sqldev 1.1 and it's located here. In the xsd you'll notice there's quite a bit that I didn't mention before.

Question #2: How to add multi-level folder like "Storage" > "Datafiles" > "Files" ?
The full xml from the first post is here. The part that will add the children is the <node/> tag which quite empty in the example. All that has to be done to add children is change the <node /> tag to something like this with PARENT_NAME being the bind for the immediate parent in the tree.
<childType id="COLUMN"">
<icon RSKEY="/path/to/my/icon.png"/>
<queries >

Question #1: How to link navigator "id" with editor "node" in the case I want to add say "SQL*Profiles" ?

The posts I did a while back explain how to get tabs added with Forgotten tabs however this has changed quite a lot in 1.1. The simpliest way now to add a tab to the broswing is to goto into the reports section and define your report exactly how you'd like to see it. Be sure to use :OBJECT_NAME , :OBJECT_TYPE , :OBJECT_OWNER as the bind variables. Then once everything is setup just right click on the report and choose Export. Export this file to some location and open it in your favorite xml editor. You'll get something that looks like this. Now in the <display tag add objectType="TABLE" Oracle will be the default for any tabs added to change to something else add connType="TimesTen".

The resulting display tag will look something like this:

<display id="" style="Table" enable="true" connType="Oracle" objectType="TABLE">

Now to add this file, it just like adding a file for the navigator. Go into the preferences and click add row , choose EDITOR.