I live in Israel for 1 and a half year now and I wanted to share this with you:
Getting around Israel should not be a problem if you don't know the language. Some people live here without speaking it.
The public transport is quite good here, there are trains from and to Tel Aviv and Jerusalem, a number of busses and sheruts (minibusses).
If the person you speak to doesn't speak English there is always someone around who does.
The road signs are always in three languages, Hebrew, English and Arabic.
Safety as a (Christian) tourist, I guess it's like any other tourist or if you live here. The last year there has been one suicide bomber in Israel, so it has been relatively quiet, apart from the war with Lebanon of course. Just check the news and the travel advice for Israel before you leave, cause things change quickly here.
The best currency to carry is Shekels. But using your credit card is no problem, it might be a problem with smaller businesses, but that't the same in other countries as well. People use credit cards for everything here, they pay for chewing gum that costs 1 dollar with their cards e.g.. You will find plenty of ATM's to get the currency as well.
Safety in certain areas:
When I am in Jerusalem I avoid the Arab quarter, because I don't feel safe there. Extreme Moslims and extreme Jews are clashing there, there are incidents on a regular basis.
I wouldn't go to the Palestinian territories, I have friends that do, but you never know what kind of fighting is going on there, there are also kidnapping happening. If you want to go there you will have to pass heavy security checkpoints, so you can't just end up there.
I personally (and a lot of Israelis with me) also don't like to go to Arab populated villages in Israel, because I don't feel safe there either. You can recognise them by the minarets and green lights on the minaret at night.
I don't want to scare you but just know which areas you are going and that there are risks involved.
If you want more info, check out my website dedicated to getting around israel with lots of info: