If you've always preferred soy, there might just be a reason why. I don't know. The symptoms you described are pretty typical for someone who is lactose intolerant, and whey is pretty much concentrated milk proteins so if you have even a very mild milk protein allergy (so mild you never noticed it before), any reaction would be much more pronounced with exposure to whey. If the problem persists when you use the whey powder, you might consider Greek yogurt, the process of making yogurt changes the structure of the milk proteins and most people tolerate it rather well even if they are allergic to milk or lactose intolerant.
On the water thing, yes it's true. Although if you have a lot to lose you might take it one goal at a time. So let's say you set a mini goal of 10% of your body weight, which would be 35 pounds, so that would be 64 oz + 30 oz = 94 oz. Use that number as a minimum level, seriously as you get used to drinking a lot of water you can increase it as you go. I totally think that 208 oz is possible, I'm at 144 so far today, and I'll be adding at least another 48 to that before bed, keep in mind I'm only slightly bigger than an elf. I've gotten so used to downing big jugs of water that I think nothing of guzzling down 32 oz at a time. Lately I've been adding a little flavor to it, I like sugar free cherry limeade and I buy the cheap store brand. It really helps to curb my sugar cravings.
Starting weight: 244.6 lbs. 10/01/09
Pounds lost: 80.6 lbs
Current weight: 164 lbs
Goal weight: 120 lbs
Weight to go: 44 lbs
Goal Date: 1/1/13