I have non-cash contributions of $400. In one area it sounds like I need to attach supporting paperwork(but not on a form) if less than a certain amount(it is). In another area it sounds like I just need to list the amount only with no supporting paperwork since the amount is small. Do they want receipts attached or not?

Do NOT attach receipts, not for $400.

They will ask for the receipts if they want proof, which is NOT likely given the amount involved.