Are all the restaurants in Israel kosher?

Places offering kosher food usually display a kashrut certificate granted to them by the local rabbinate. Most hotels serve kosher food, as well as some restaurants. But there is no binding law. So if kashrut is important to you, you must check it out at each separate place where you dine.

Is everything closed on Shabbat in Israel?

All public offices in Israel are closed on Shabbat, as are most private businesses. In most cities, public transportation (trains and buses) does not operate, and most, but not all, restaurants are closed. Radio and TV broadcasts operate as usual.
From The Israel Ministry of Tourism