"...sources of fuel for energy and what macronutrients (carbohydrates, fats, proteins) you consume will not alter urine color."
I do not believe this is true. Uric acid, a break down product from metabolizing fats and protiens is the primary coloring agent for urine. It is yellow to brownish in color. It is normally excreted through the urine. There are two avenues for the color of the urine. First is water: too much can dilute it a lot, or, too little can cause it to become very concentrated. This is what most hikers think of as watching your urine color. Second is the uric acid itself: producing more or less depends on your diet/excersize level. Eating a large amount of beef jerkey for example will cause your urine to be more yellow without effecting the bodies homeostasis. The excess protien the body does NOT need will be metabolized for energy, causing the nitrogen radical (urea cycle), to be excreted. A normal person's urine color can change over many shades with no hint of dehydration. High protien diets (fresh fish and chicken for example) often cause very yellow urine, despite drinking adequtly (and without the salt usually found in beef jerky.)
"Most of the uric acid is removed from the body in urine. A small amount passes out of the body in stool. But if too much uric acid is being produced, the level in the urine will increase. If the kidneys are not able to remove it from the blood normally, the level of uric acid in the urine will decrease."
Yes. In hot weather (the primary subject here) you sweat. A large amount of eric acid passes out of your body through the sweat. In this context, your skin becomes an organ of excretion, too. This was exactly my point above without the more technical details, of course.
"... Drinking water, even in large amounts, will not flush electrolytes. The kidney is very good at adjusting electrolyte and water compositions as needed. It is, however, good advice to not force water down if you are not thirsty(with the exception of those reaching a level of dehydration and exhaustion where the body's normal thirst mechanisms are compromised)."
Generally yes, I will agree with you. But we are talking about a person sweating a lot of salt out, ie, within normal conditions, but on the low end. Drinking more than you need in such a situation will act as a "sponge" causing the salts to flood into the water. You can easly loose too many salts and go into a hypernatrial state. Be a bit carefull about drinking lots of water with no electrolytes. I just did that on the NPT, drinking more than I needed at a cold stream. I got a bit disoriented and nasueous. I had to sit down and think a minute before recognizing I needed some salt, too. The big clues were I was soaked with sweat, 90+F day, hiking fairly hard for over 2 hours, ate a little, but only a couple bites. I finished my water bottle, filled them up zapped them and drank them, filled them up and zapped them and packed up to leave. About a liter and a half was enough to make me very light headed. This is BEFORE the water even hit my kidneys, maybe 7-8 minutes.