Not trying to rain on your parade here, but that is NOT cyano bacteria, and you cant kill cyano with low lighting... I believe it was ReefkeeperZ that did that test? First off thats a really poor picture and hard to tell exactly what were looking at.
The brown "algae" is diatoms like 44 said. Those are always going to show up in new tanks... Why are you telling him to take the damsels back??? They've been in there 3 weeks!?! Might as well at least let them cycle even if he is going to take them back somewhere... If they're blue/green chromis he wont even have to worry about them messing with new additions...
44 Is on point with seeding your dead rock with LR and with the 10% water changes... You dont need to do 30%, especially twice a week. If I was you I'd get a 5 gallon bucket and use that for weekly water changes. With your live rock and all putting you at more like 50 gallons - that makes 10%.
And did I read right that you dont have a clean up crew??? If thats the case, no wonder your having a phosphate issue. Phosphates come from excess nutrients in the water. Like all the uneaten food you talked about. I would recommend some nassarius snails for that. They bury themselves under the sand and when food hits the water its like night of the living dead. They're great for stirring the sand bed and picking up that uneaten food. Hermits are good too, but then you gotta deal with empty shells and them attacking snails etc etc... Still a good addition anyway - its really more of a personal preference. Some people dont like hermits.
Ok I'm done writing my book - hope this helped...