If I understand correctly, you now have a 2 year contract on that iPad line? Did you transfer the upgrade from the iPad to the line for the iPhone 5s or actually UPGRADE the iPad line to an iPhone 5s? If you transferred an upgrade, you don't need to do anything really. Just activate the 5s as normal.
If not, then the 5s will need to first be activated under the iPad line, then you can get a new nano sim to put in the phone tied to your line you want it to be on and put the other sim in the iPad. This will probably require a trip to the Verizon store (yuck) or a call to customer service (also yuck) at the very least.