Well, I'm no PG, but I could give you some pointers.
First of all, yes, the "spazzy fangirl" aspect should really be taken down a couple of notches - we all enjoy a good discussion about our favorite fandoms and characters, but it could be a little too much for some people if it's taken to the extreme. You do not need to emphasize that you have an embarassing RP or use capslock in subject headers to show you're excited, if you catch my drift, Li'l Pink Ranger =P
On the topic of Fanon, please do keep in mind that not everyone may know what you're referring to (as is the nature of most in-jokes), and that in most cases, we will refer to the canon instead of the fanon, as there can be many different kinds of fans and fanons of a franchise, some more extreme than the others. Please respect the fans who are not interested in fan theories.
Now, something that might sound less like scolding and finger-waggling is that you should probably read a couple of different PPCers' spinoffs - TOS is a good place to start, but since then, a lot has changed in the PPC's own canon: New rules have been established, new characters have been introduced, new tools have been invented, and missions might be approached differently (depending on the author).
Your characters have really improved from the last attempts, so you might want to experiment with how they work together (you might want to play it out in a document you keep to yourself until you've figured out where you want to take each of them in the sense of character arcs), and try to get a "feel" for them, so you can automatically recall how to write them - maybe you could even make your Permission piece something pertaining to how your agents met, or detailing the backstory of one of the two.
If you're successful and get Permission, please don't just jump at the first mission you encounter. Depending on the fanfic you target, you will need a lot of planning and perhaps even have to do some research into the canon. You can always try asking here or in the IRC for some advice if you get stuck, nobody will be mad at you if you aren't able to do your first mission all by yourself (and nobody really expects this from you, either - that's what a community is for!).
So just stick around for a while, talk, make some friends, and enjoy what the other PPCers have already written first.
I hope this helps you a little, and good luck on your next attempt - but please don't rush things and run your sample by a beta reader before posting it. We don't have deadlines, and while the above might sound a bit strict, we do want you to have fun doing this, after all! =D
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