Jb
I'm afraid there is virtually no legislation controlling the operation of an MR and only slightly more ruiles.
It is standard procedure for the MR to be done by a different and usually more senior Decision Maker than the one that made the original Decision.
I'm not aware of any requirement for any subsequent MR to be carried out by a third DM, in fact, strictly speaking there is no such thing as a 2nd MR, legally the DWP have discharged their responsibility once they have done one MR.
Yes, the DWP submission will include all of the papers involved in the making of the Decision and the MR, this will include, at the very least, your original claim form and anything attached, the assessment report and anything you submitted as part of the MR.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
