DC discount is 5%. One day passes are one day passes usable at any park. They are not specific.
I would think that the postage to get the GC's from Wal*Mart would cut into the savings a bit.
Wal*Mart does not sell annuals, BUT, if you wish to appreciate the savings, buy any pass and upgrade it for an annual at WDW.
After reading the Wal*Mart site it seems apparent that Wal*Mart owns the
travel agency, so, I am sure they would honor the GCs.
As to using different codes for different orders,
I have no clue. I just purchased my annuals via the phone yesterday (OUCH!!!!!). But, I get three trips out of them, so, it works well for me.
Gail
Offsite - 88
CBR - 89 & 90
PO - 91
OKW-92,OKW-93,OKW-96, OKW-97 2X'S,OKW-98 2X's
OKW-99 2X'S,OKW-00 2X's
Jamaica-SandalsInn 98&00