Re: Is this NEWBIE out of his league buying this boat??? Be honest...
OP, good advice. Don't get discouraged, you live in a spectacular area for boating, and have the green light from the Admiral.
Take your time, look around, rent a few craft. Focus on what you think you'll be doing most, as you have described a pretty wide spectrum of boating, namely: (1) trailering to inland lakes, to (2) Mission Bay, to (3) 39 Mile Open Water trip from Long Beach to Catalina.
For instance, even though you can make the crossing to Catalina in an hour +/- depending upon conditions and craft, I would want a larger seaworthy boat for the Pacific Ocean, biased towards outboard and open self-bailing deck, VHF radio, small head. Perhaps opposite for inland lakes and say watersports, which could tilt you towards a smaller I/O. Do you really want a sleep aboard cuddy? Are you wanting to fish? Watersports? Will you consider a slip in Mission Bay or Long Beach?
Have fun with it, look and pilot a ton of boats. Make the crossing to Catalina and look around that marina, along with the lakes and bays you are most interested in boating. While it is always good to progess from a starter boat, you also want to get the proper category of craft suited to your useage.