Encoding multiple fields with same AES key and vector?
Speaking in broad strokes, reuse of the key is fine - reuse of the IV: not fine.  From wikipedia: "Properties of an IV depend on the cryptographic scheme used. A basic requirement is uniqueness, which means that no IV may be reused under the same key".  You also need to decide on a mode of operation, as different modes will dictate different requirements for the IV/nonce.