There is a Super
Walmart right on Turkey Lake Road:
http://www.walmart.com/storeLocator/ca_storefinder_details_short.do?edit_object_id=4332
and there is a CVS Pharmacy right on the corner by the Residence Inn SW, which has many of the things you might need (unless a major grocery run is needed).
I-Drive can get VERY congested, particularly on the north end (near Universal). The south end (by SeaWorld) is generally much more civilized

. The closer you get to Sand Lake Road, the busier it gets.