A lot of Asian gils do have very fucked up ideas of how heavy girls should be some think they're only at the right weight if they're underweight but that doesn't mean you have to buy into that. I also don't think they apply the same standards to western women. You can look any way you want pretty much. I think a lot of Asians (both genders) admire more curvy bodies because it's different from what they're used to so it's more attractive to them. But that's just from what I've seen so not 100% reliable. Anyway you shouldn't be this worried about it, just go there and have fun.
Depends on the country, but most would consider you to be average. What Szafi said is true though. Just be prepared to receive looks and comments about your appearance; they won't be shy to point out if you've gained a bit of weight or lost some, but they won't mean to be insulting.
Where in Asia? I lived in China for a few years. If you're going to China you will be stared at in any place that's not a major city. Even in major cities you may attract a lot of attention. Not because you are fat, though. They're going to love you because you are white.
No way. Google search Asian girls and you'll see that you practically have the same body size. And it's a perfect body, too. Don't go on any serious diet, because you don't need it. Maybe just focus on eating healthy foods, and eat less sugars/fats/carbs. That's really all you can do.
This is a non-issue when you're not Asian. As I told you before, you'll be seen as gaijin, looked down upon or viewed as a public attraction. They will never see you as one of them. You will always stick out. Deal with it.