Low you have to ask yourself do you want the SNA Billet more or the scholarship. Cause Pat is right about getting the slot early for a SNA billet in BDCP, but your tuition will not be paid for. So if you go ROTC you will have your scholarship but have to wait for your billet assignment till your an upperclassmen. Thats the trade off. But from what I hear ROTC do get first select for that Fiscal Year they are graduating.
In Sea Cadets there is dues but not much, its for insurance and some units might add unit dues also. It depends on the unit you join. And you just sign up, but you must also have good grades.
Here is the CA unit Locator link: http://dolphin.seacadets.org/US_units/unitlist.asp?stateid=ca
Again get boot camp done and you can start heading to Basic Airmen and then Advance meeting some real NA, NFO and Enlisted Techs that help conduct the training. Plus FAA Ground school.
I have heard that the TOMCAT is planning to retire in 2010. By that time it will be one VF squadron to retire. The Navy has already transition some VF Sqn to VFA already...Look at the Diamondbacks they got the SuperBug now. And there CO and XO are NFO, thats pretty cool to me. They are keeping the monkey in check and where to go. How do you like that for some of you NFO haters. Good luck and you can keep on dreamin about the Tomcat, Low.