Feeding Question

I have a 90 gallon setup that has about 100 pounds of live rock with a typical
sump system ( with G1 skimmer inside ). I have a 2 bubble tip anenomes, a
feather duster and a frog spawn coral.

My concern is that I am really not sure how much food I should be feeding the
fish. Here is a list of the fish...(2) clowns, (1) Domino Damsel, (1) Blue
Damsel, (1) Midas Blenny, (1) Blue Tang and (1) Spotted Prawn Goby. I know
that for the most part fish will eat when ever food is offered so I know that
overfeeing could occur very easily. I have a mild algae problem that is
starting to subside since the coraline algae has started to take off.

I feed a mix of several different frozen foods....the "ice cube" type that you
typically see at the LFS. How much food do you think that I should be feeding?
How often...daily? My main concern is the Goby because he is very mellow but
gets kind of "snappy" when I know that not much food has gotten down to the
bottom for him. I really don't want to go through the hassle of removing him
from the tank because I would have to disturb too much of the rock/established
environment.

Also, any tips on removing hair algae from live rock without taking it out and
scrubbing it?