Hey now that very tank is a 10g with 15w - That's pretty high for my standards

in the back part, pretty much directly under the lights its about 1" tall in the front part where its getting less light it grows taller, but I just trim it.
Hmm you mean diatoms? What's the water parameters?
I donno how good friends are you with the guys from the hardware store, my guys here lemme buy a bulb and if its really too bright return it and exchange for another one. But I'd really not think a 36" 20w would be too strong.
That whole watt per gallon matter used to work GREAT back in the days when everybody had T12 only over tanks. Now having T8 and CFL and what not that really does not apply any longer. For example you can buy CFLs that *use* 7w of power, however the intensity of light they give off is actually 40w...so that whole wpg is wayyy out the window seriously.
If you personally do not like this, don't do it

I can only suggest what works for me and has worked in the past and I think my tank pic's are a lil proof of that too. But if it ain't your piece of cake, don't eat it
I'm not trying to breed my Cory's however they do lay eggs extremely regularly with a storm, especially the Bronze one's. That said the second 1 gal lay's eggs on glass/ leaf there's about 8 other cory's ganging up behind her with another 8 Tiger Barbs and all them snack down the eggs SECONDS after they're layed. So unless you wanna do some night time watch with the flashlight and tricky set ups with mesh on the bottom etc etc I'd say don't breed cory's.
That said I'm therefore quite sure the Cory's would also eat the Tetra fry and the CPO fry. Personally I'm raising my Killi fry (which is about as small of a fish as its ever gonna get) with my Red Cherry; alternatively I'd go for CPO and then also raise some CPO baby's but i'd not add cory cats in that mix.
Easiest way to move shrimp if you want to: Get a smaller coke bottle cleaned out, cut the 'neck' of where the bottle is not angled any more; turn this neck inside out into the bottle and fill it with tank water and bottom feeder pills. Shrimp of all sizes will go in to it to eat but somehow thou its open they don't go back out of there. Easiest and most unstressful way to catch them all
RCS breed unlimited by themselves so that's super simple as long as you got a good water quality.
Tetra's I never tried breeding so I can tell you little about this.
Cory's like I said I'd do a sep set up specifically to breed just them (10g for 1 pair?)