Is one JWP sufficient to handle our Production Environment? Reason I ask is we will be allowing our users to start using the Web GUI to search for their own objects and thought one JWP would not handle the added load?
You don't need more JWP for that. The JWP is a component of the Automation Engine which is required for the following functions:
Single Sign-on (via KDC)
Adaptive ERT calculation
Function Export with references
Application Release Automation Integration
ECC Global Search
Here are the sizing requirements for your reference: