Scott, I'm an engineer at NAS North Island with the F/A-18 A-F Avionics Team, so I'm pretty qualified to answer this. I also leave for OCS next summer.
The A/B-model Hornets are primarily flown by strike/weapons test folks. There are some A's and B's in the RAG squadrons though. Most of the early A-model birds went through something called the A+ program, which takes an A-model and essentially makes it a C-model(avionically speaking).
Right now the E/F's are not replacing any existing Hornet activities, they're replacing F-14 and some old A-6 squadrons. VFA-41, was a prior tomcat squadron(VF-41), now flying the F-model. VFA-115, was a prior A-6 squadron(VA-115), now flying the E-model. VFA-14 is also flying the E-model. Currently, these are the only three non-RAG squadrons, and they are all in Lemoore.
2003, 2004, 2005 are big years for the E/F program. Many old tomcat squadrons are getting brand new F's and the Super Hornet will make it's way to the East Coast(Oceana). Also, we will see some existing Hornet activities get the E/F model in 2005.
Slick