popup questions

I'm OK with the idea of a help button that is a
  link_to (.... :popup
that produce a modal box.

Q1: Can I make it produce a non-modal box?
     So the help text stays up but the user can continue working?

But I'm trying to to deal with modal dialogue boxes.
The most obvious one is a logo box. I'd like to do the login without
actually changing the page behind the dialogue box.

Q2: Can :popup produce dialogue boxes? I presume they would be based on
     partial, but would they need special actions

Its nice to have a 'login' pop-up from a link_to button but suppose I
need that same UI popup generated programatically.

  def read

     if ! @page.acllist.nil? # page has restricted access
       if @current_user.nil?
    begin
        # trigger login dialogue box if javascript *****
        # redirect to login page if no javascript *****

    end
      # either logged in or not
            if @current_user.nil
    raise Application::AccessControlError \
                                  "You must be logged in
          return false
            end
            if @page.acllist["read"].include(@current_user.name).nil?
    raise Application::AccessControlError \
      "You don't have permission to read that"
    return false
      end
      ..... # continue processing page

Q3: Is there a way to determine if javascript is available?
    Failing that, how can the "if javascript then ...
                               else redirect and return here"
    be handled?

Q4: Will things in the controller actually be updated by a modal
    dialogue box? Or would I have to re-scan the database to
    update @current_user? How would I cope with non-database
    variables? Suppose the modal dialogue box asked for a discount
    code?

Q5: Can I link error handling to dialogue boxes?
    If so, how can I hand over more parameters (e.g. a redirect to
    as opposed to a 'stay where you are')?

I know that's a lot for one post, but as you see the questions are
related and I'm sure this is something a lot of other people would find
useful.