Should i include a few pieces of the cardstock such as visor and the lights that i have folded when i go to resin and bondo etc? or would it be easier to work with to leave those pieces out?
You should leave those in so that your helmet keeps it shape as you resin it and all that hardening goodness. If you really want to leave those parts out, you will need to add in support struts.
Next time use the 'Pepakura or Papercraft' or 'Fiberglassing, Resining, & Bondo' stickies for your questions.