I can tell you that the ornament effect
Increase land speed does not stack with the EX effect
Increase land speed, instead the higher rank is used, just like if you use more then one EX item with the same effect.
Works probably the same for all the other Ex/Ornament effects.
Ornament effect ranks depend on how many ornament points you got.
10 Points=Rank1
30 Points=Rank2
50 Points (needs a full ornamnet room, all with +5)=Rank3
You can check your ornament effects with "Journal->Ornament Display Effects" (If you have a rank5 quarter with a ornament display room)