SouthPawPete saidAs for salt proportions, I stick to the crock manufacturer's recommendations: 5-8gm(15gm max.) per kg of contents. Their brine recommendation is 15gm per liter. And only sea salt. Iodine plays havoc with the bacteria.
In Linda Ziedrich's book that I referenced above she says,
If you want fully sour pickles that aren't overly salty, use a 5 percent brine; at room temperature the fermentation will last two to four weeks. Full-sours are suitable for canning.
If you like salty pickles and want a slower fermentation--of six to eight weeks, say---use a 7 to 8 percent brine. With stronger brines, though, lactic-acid fermentation happens more slowly, so more yeast and gas develop, and cucumber pickles often become "bloaters"-- hollow, floating pickles. Mold is more likely to develop, too.
She then has some tables that I found less than helpful and confusing, partly because she specifies a gallon of water, which is way more than I want because I use a wide mouth quart jar.
If you use a digital scale and have a calculator that does percentages (e.g., MobiCalc for Android) it turns out to be trivially easy. If you're not sure you're pressing the right buttons on your calculator calculate a percentage of 100; for example, 8% of 100 should be 8, 5% of 100 should be 5, etc. Once you've got that part figured out then you can plug in any quantity you want.
A quart of water is 4 cups, and a cup of water weights about 250 grams, so I could start with 1000 grams of water (aka a liter).
5% of 1000 grams is 50 grams. Take a container that holds a little more than a liter. But maybe that's too much, so let's start with half a liter, or 500 grams of water. Which means that our 5% of salt drops to 25 grams. Put your quart jar on the scale, zero the scale, and put in 25 grams of pickling salt. Now add enough water to bring the weight up to 500 grams. And, et voilà, you have a 5% brine. So now if you want to make a 6% or 7% brine solution, or start with 400 grams of water, it's easy as pie. Basically you subtract from the total water the weight of the salt, but rather than do the math let your digital scale do it for you.