Unfortunately, all of those questions have completely arbitrary answers.
However, in my opinion: yes, your phosphates are too high. You want to see them much lower, .1 or less, ideally .03-.06. That will hinder nuisance algae from growing and allow your clean up crew to take care of things while still allowing your corals the necessary nutrients to grow.
as for food: there are a million+1 different things you can put in your tank, all of which claim to grow massive colorful corals. Reef Chili is a good option, also Reef roids is something that is very common (because it works) but use sparingly because it will also grow algae! Same with amino acids, like Fuel or Red Sea A+B.
for me, I dose amino acids every other day, and feed a small amount of Reef Nutritions Phyto Feast and Oyster Feast every day. It took a while for my tank to adjust to that much feeding, and I definitely wouldn’t recommend that to a new tank!
Maybe try starting with some aminos once a week, and broadcast some reef roids twice a week and see how that goes. As your corals start to grow, (and you get more corals!) you can try increasing the amount and frequency of your feeding.
you will no doubt see some algae anytime you start adding nutrients to your system. Don’t panic: this is normal. Allow your tank time to adjust, and make sure you have an adequate CUC.
