You can generally eyeball the weight of cheese you cut from a block, then grate and measure.

You have to be careful with conversions. 4 ounces of sugar in volume isn't the same as 4 ounces of flour or 4 ounces of cheese. Find a good specific conversion guide and make a personal document of your most often used ingredients. I've taped mine to the inside of a cupboard door where I do most of my mixing. I also have a scale that helps for metric weight to ounce conversions, but don't use it as often as I know I should.

It depends. But for a medium grate you can use a conversion of 1/4 lb of cheese will equal 1 cup grated.

I tend to rely on this great list from King Arthur: http://www.kingarthurflour.com/recipes2008/master-weight-chart.html According to them 1cup grated cheddar = 4 oz.

I'm usually converting *into* weights from volumen measurements, but it works both ways.