Another candidate for the finnex 4 gal club.
I think you are on the right track but I do have a few suggestions. I am not a fan of flourite, I used it in my finnex at first also and i didnt like the look of it. I do like eco alot but you will only need half of the bag. Why not get a 3 litre bag of aquasoil, its actually cheaper than a bag of eco and you can use the whole bag and not have any left over.
I dont know much about the reg you have there but it looks nice and its more affordable than the Red Sea one which doesn't have a selenoid. TOFTT and try it out and then let us all know about it.
As far as the diffuser take a look at this
one I posted about in another thread.
Heater, you live in San Diego. I've never been there personally but come on. If anything you should just go with the little hydor that regulates the temp a couple of degrees. I have one if you need one. PM me.
5 neons are definately too much for this tank, plus I think they suggest at least 6-7 of them together. Microrasboras are definately the way to go if you want fish in there. Holla at Pedro he has them. The RCS and otto shouldn't be a problem though.
As far as lights go remember the 3 watts per gallon rule doesn't apply to nano tanks so the 13 watt light that comes with the finnex doesnt grow many high light plants, especially foreground plants. I would suggest at least the Home Depot $20 light to go along with the finnex light or the Ott - lights that Ugly genius uses. You should be able to grow anything with that. Plant selection so far looks great though.
Hurry up and get this thang going and post plenty of pics.