1. You have to go by weight....volume is not accurate as sugar is more dense than water so it does not take as much to be that same amount as water.
2. Add the sugar to the water and stir... you do not need to add heat until the mixture is fully saturated which is up around 2:1.. The sucrose will form bonds with the H20 until the solution is saturated at which point sugar crystals will pile up at the bottom of the mixing container.... when that happens you need to add heat to increase solubility...but you should not be feeding bees anything that over 2:1 anyway.
Good Judgement comes from Experience. Experience comes from Poor Judgement.