question 1: i would run only and inch to inch and half..... wouldnt rely on sand as filtration your fuge can do rest or use bio pellets to help with filtration.... i dont like depending on sand beds as part of filtration(ticking time bomb)

question 2: i gauge my skim on how dark it it not smell lol.... dark means im skimming dry and light green means wet skim.....so do what you like as long as it skimming