In order to answer your first question properly there needs to be more information given.
What type of medium are you using? Hydro, soil or soilless (coco coir, hydroton, perlite, sand, gravel, what have you)
Soil is forgiving and will buffer any nutrient application mistakes you might make. As far as I'm concerned, it's superior to straight up Hydro in this fact alone. The ONLY advantage, for the plants, to going hydro is to increase your yields and possibly decrease your flower time by a couple of days. There are no other advantages to hydro over soil. This is my opinion, peeps, so don't try to argue with it! If ya wanna say it's cleaner than soil I'll just call ya a slob. Cleanliness is up to you no matter what medium you are using. Spilled water and chems don't clean themselves up.
What kind of water are you using? (Tap, distilled, RO, bottled)
RO and Distilled are the best. They should have 0 PPM, 0 TDS, 0 EC and pH 7. If ya dont have an RO maker I'd get one. Using any other water source, you need to be aware of what is in it.
THE SUGAR QUESTION:
Don't use bleached white sugar... All of the nutritional value has been removed by in processing it and is there fore useless for your soil (micro guys) and you. (That's the reason white sugar is referred to as "empty carbs")
Molasses, however, is great stuff used in moderation. (1/8 to 1/4 tsp per gal H2O) It contains Iron, Calcium and Potassium that will be released once the micro guys in your soil eat it.
USE ONLY UNSULPHURED MOLASSES. Blackstrap being the best.