Can I allow a user to create a Node using only an embeded rich text editor
I have done this using:


Automatic Node Titles Module



  "auto_nodetitle" is a small and efficient module that allows hiding of
  the content title field in the form. To prevent empty content title
  fields one can configure it to generate the title by a given pattern.



Advanced Form Block Module



  Welcome to Advanced Form Block Module. With this module you can do the
  following:
  
  1) Create any number of blocks with a particular node edit form.
  
  2) create any number of blocks with a particular node add form of a
  content type.
  
  3) Create as many blocks as you like of each kind.
  
  4) From the content type choose which fields to display on a per block
  basis.However required fields will be automatically displayed.
  
  5) All forms will be saved through ajax. So multiple node forms can be
  independently placed on a single page and worked with simultaneously.


With configuration and some css, you can get it looking really nice, and as a block it can go anywhere you want. You can also use hook_form_alter() on the appropriate form:

$form['actions']['submit']['#value'] = 'BUTTON TEXT';

to change the text of the submit button