The amount of water per day doesn't seem to really depend on height, but rather how much weight you'd like to lose, and more can't really hurt.
If you're drinking 2L (a little more than 8 cups, by U.S. measurements) of water a day, you're getting a bit over the daily recommended amount. A lot of common thought here says that you should drink that amount (roughly 2L) and then about 1/4L more for every 10 lbs. you'd like to lose.
I hope you can get more tofu soon! I admit I know little about a vegan diet as I do eat meat and animal products, and if you're comfortable with the protein you're getting now, that's good. I just knew it helped for me!
Lowering sodium is always good for the heart; I just know that if I have a "high-sodium day" (usually due to eating out) that I will retain water for a couple of days until the sodium flushes out of my system, but if it's not a problem for you, then great!
Plateaus can go on anywhere from a couple of weeks to months and months... they're usually not a serious problem, and they happen to everyone. As long as you're feeling healthy and know you are eating in your limits, it's probably okay to plateau without having to worry about it (though they are very frustrating). Happens to everyone - and the closer you get towards a goal weight, the harder it is to lose.
Female, 31 years old, 5'4 1/2" tall
Starting weight 1/4/11 = 215.2 lbs.
Weight 9/8/14 = 178.8 (net: -36.4)
Last mini-goal: 180 lbs. REACHED! Reward - new sports bra
Current min-goal: 175 lbs.
Next large goal: 165 lbs. by 12/25/2014
Lowest weight: 156.7 lbs.
150.2 lbs. <--- Official "Healthy BMI" weight
Estimated final goal: 130-140 lbs.
"You don't have to change your life today. You only need to change your day today."