Dairy in Israel

Question

We recently made aliyah from the States where we ate kosher non-chalav yisrael. Since coming to Israel we have become very confused about what is permissible for someone who cares about kashrut and what is kosher according to the Rabbanut (which we have been told is a minimal standard of kashrut so at least those who wouldn't go out of their way to eat kosher are not eating treif). Till now we have been relying on a rav in Israel who works for a major American kashrut organization, for answers regarding kashrut. However, we are no longer comfortable with depending solely on his psak. We have found this issue of mehadrin vs non-mehadrin confusing and divisive since there are many frum people who eat plain rabbanut and we seem to have to pick and choose which frum friends' homes are acceptable to eat in. 1) In a reply to someone else on this forum (forum/viewpost.asp?mid=2883&highlight=) you said that milk in all civilized countries is Cholov Yisrael. Why then does Israel require certain dairy products to be listed as Chalav Nochri? 2) We have been told by this rav that non-mehadrin dairy in Israel could have been milked on Shabbat and therefore really shouldn't be used. What is your opinion? 3) I have heard that there is a problem with milk from cows in the United States (and elsewhere?). Because of the way they're fed now, their abdomens become bloated and are punctured to let out the gas, often rendering the cows treif. We were told that this is not an issue in Israel because of the care taken in puncturing the stomachs. Is this something to be concerned about regarding dairy products from the U.S.? Does this affect your answer to my first question?