yes regular sugar will work
No you should NOT use white sugar used for coffee, it is bleached(so are coffee beans) use 100% natural cane sugar or raw sugar (its yellowish) or natural brown sugar(this is raw sugar and molasses mixed)
Grandmas unsulphured mollasses provides carbohydrates, sugars, potassium, calcium, magnesium, and iron as well as 'food' for beneficial bacteria in the dirt(sugars) to help the roots colonize. What the mollasses provides is brand specific, just read the nutrients table,
sugars and carbs help it convert energy from the light better and the mag will keep it greener as long as N it up to par making the plant able to use more light during the daylight period. This also helps the plant produce enzymes and hormones needed to stay hearty during its life cycle.
Anything you feed a plant must be UNSULPHURED. Gatorade/powerade anything that has an ingredient listed as a sulfate will cause your roots to stock taking up water because it will produce insane amounts of salt deposits on the roots.
In theory your idea about cutting around the stock could work. BUT you have to take into consideration, if your using chemical fertilizers, and if you don't check your moisture level daily(if using dirt) you are GOING to have some roots that die out. Not to mention the larger roots leaching usable water from the smaller roots. If you do this too early the roots won't be able to replace the roots that are lost. As you know root mass it relative to leaf/plant mass.
If you don't have enough roots to take up nutrients to fully support the plant it will spread out what it is taking up just for survival. Even if you could grow through the whole 8-12 week flower period like this, the stress it would cause would be detramental to the crop size and quality.
IF you ARE going to try this the best time would be the Last time you give your plants fertilizers.
If you do try it at the beginning I would get a vitamin or hormone supplement such as Superthrive just so the roots can produce mass by themselves and the plant won't be as stressed because of the better internal enzyme balance created by the vitamins.
My buddy is pretty scientific on this shit, we were actually just talking about a similar technique. By cutting off the 2 bottom nodes/shoots at the stalk about 3 weeks into flowering(or when all tips have established small hair balls) it will not try to regenerate there and it will do like you said. It will block the sugars from going down past that point, because once that part heals it gets a hard dry spot on the inside there. by doing the bottom 2 nodes you create a 'crossroads in the stem' and it greatly reduces sugar loss without damaging the stalk and without completely cutting off the roots.
This also causes the plant to concentrate its flowering into the top buds to better attract pollen since it recognizes it will be down potentially 4 flowers. But realistically they're just gonna be the popcorn buds at the bottom anyways.
Its important to wait until they're in full flower, no tweeners or you'll stress it and itll hermie.