Depending on the issuing jurisdiction, it won't be California, there may be a website where you can pay one or both tickets.

As to the missing plate, just be careful that it does get paid. Otherwise it won't, the ticket will come in from the jurisdiction, Hertz will pay it and charge you + admin fee. You will then have to engage in a lengthy fight with Hertz to get rid of it..

As an aside, I always check the plates, registration & inspection as part of my vehicle check for damage. Can't tell you how many times something is missing or expired.