I think you are setting yourself a difficult task of learning Arabic and learning how to teach young children. If you stay focused it could work. I would focus on specific phrases in Arabic. The phrases that will be useful for you to learn are:
Instructions on how to play games and carry out activities.
You can learn basic classroom instructions in advance; e.g. listen to me, look at this, come and sit down, stand up. You can use Arabic at the beginning but it will be helpful if you start teaching this meta-language in English to the children after a few lessons. As for the instructions for how to play a game or carry out any other activity, that will depend on the game. You will only be able to work out what language is needed after you have planned your lesson. Once you are in the country, you may find a person who can help you with these translations. As for introductions, you will probably only teach them my name is…… and I am ….. years old in the first lesson and it may be a good idea to learn that in Arabic to help them along.
I think the most important thing is for you to learn ways of teaching these children through the medium of English. You’ll need lots of flash cards, you’ll be able to use mime and demonstration. Sometimes you can take in objects to help teach them. Children learn a lot through playing, singing, mimicking and listening to stories. You’ll need a battery of these activities to get you through the first weeks. Children also need and like a lot of repetition; they will happily sing the same song every lesson; so don’t hesitate to do that.
Your question is quite general. I suggest you go through this forum where I have answered a lot of questions on specific issues related to teaching children; there is also a forum on teaching young learners. Also buy a good book on how to teach young learners and find out from your school what time of material, objects, equipment and books are available for your use.
All the best,