what order does all the stuff in the invites go?

I don't know about the order of things, not sure it matters but this is from invitationoutlet

Fold all Invitations and Response cards with the wording facing front.
Place stamp on return Response envelope.
Place Response card under flap of return envelope.
Place Reception card on top of Response card.
If you are using tissues, place a tissue on top of Invitation.
(FYI: The tissue is an ancient practice that dates back to when invitations were hand written in pen and ink. The tissue helped keep the wet ink from smearing itself and the other enclosure cards.)
Place all enclosure cards on top of the tissue covering the invitation or
you can place all enclosure cards inside a folding card.
Slide all cards into envelope. If using double envelopes, slide all cards into the inner
envelope, then turn it over so the front with the names of your guests is facing you.
Slide inner envelope into outer pre-addressed stamped envelope.
Take one fully assembled invitation to the post office for weight and size.