Hi Tommy,
I'll try to answer your questions as best I can. I attempted to hike the trail last year, (only made about 5 days before I hurt my ankle), but these are from my experience.
1. As Yankale said 2-3 weeks is plenty of time. This of course depends on how long you plan to hike each day, and if you want to lay over in a town. I would suggest not worrying so much about making it from point A to point B, just enjoy the places you make it to each day!
2. Yankale's list will be a benefit to you. Don't worry about food, there are PLENTY of places along the way to get supplies. Be more concerned with how much water you are carrying. There are places to get refilled in the North, but if you run out in between you're kind of stuck. (Trust me, I know this one from experience) :D
3. See above. I made the mistake of taking 2-3 days of food supplies starting from Dan and ended up dumping the majority of it when I reached Tel Hai. (1st day)
4. I'll also put a plug in for Yankale's book, it is very informative and worth the purchase. As far as the Hebrew, you will be plesently surprised that the majority of Israeli people speak better English than you or I. I was surprised by this fact, but it was VERY helpful. Also worth mentioning is the attitude and friendliness of people on the trail, (at least everyone I met). I don't believe I met a single person who would not, (or did not) go out of their way to help me when I needed it.
5. I didn't find any churches along the way, (I didn't make it very far either), but if you google Christian churches in Israel you will find a good list with worship times.
If you have any other questions, just ask. This forum is full of VERY helpful people.
Have a great time, and may the Lord bless you and keep you on the trail!
Your brother in Christ,
Billy