1. In the lib folder is the best place. If you are doing more than small modifications you might consider wrapping it up as a Rails plugin instead.
2. Either in application_helper.rb or in their own separate files (in the lib folder) which you can then mixin to ApplicationHelper. Not sure why that isn't working for you, I've never had problems with it. I may be missing something obvious that somebody else could point out.
@data = @dbman.restore
# Filters added to this controller will be run for all controllers in the application.
# Likewise, all the methods added will be available for all controllers.
class ApplicationController < ActionController::Base
#format methods for class Numeric String Time
#session as a hash for class CGI::Session
2. Making a helper available to each and every controller