someone else can chime in if they feel im wrong on that.. but 0 nitrates in a 5 month established tank sounds kooky.... lol
I agree about the nitrates. You should have something there if you have anything alive in the tank. And without live plants to soak up the nitrates I would expect them to read higher.
As for the white stuff on driftwood...it is likely brown algae/diatoms. They appear typically in association with high nitrates and silicates, and often with weak lighting. What type of lighting do you have? They will work themselves out with increased light in a cycled tank. Would not hurt to add some otocinclus or another algae eater to the tank like a pleco, even though I don't prefer plecos. There are a number of other great community algae eaters you can of course consider.
I already mentioned how overstocked I think your tank is. And even if you are not interested in breeding angels as you have stated, you can not force them to be celebate as they mature. They will pair up, and with the numbers you are keeping...you may get more than one pair. They will become aggressive and territorial and as HN1 said...anything but angels.
I have a friend who sells off pairs once they faithfully produce, and she makes a good income at this. But to be certain you will not be able to stock your tank with that many angels for very long. I love angels too. They are beautiful fish, but I would recommend against waiting until they mature and become aggressive and territorial to find homes different homes for them.
I suggest looking for a pair amongst the school that you have and then selling back the rest to the breeder or to interested buyers. If you get lucky, or unlucky, depending on your perspective, and get several pairs, you will need a tank per pair. I say this as I don't think your 65 gallon is even large enough to divide more than once or twice with plexi screens to seperate pairs without too much stress. Do you have other tanks that you could move some into?