The game data is stored on your device. You will need a program that allows you to access this data. I can not recommend any such software personally, however once you have this the game data can be found
/Documents/games/com.mojang/minecraftWorlds/<WorldName>
You should be able to use the same software to download the necessary files, and then transfer them to your new phone.
You should also be able to use iTunes to back up your old phone, and then restore it to a new phone, even if they have different basebands but provided they are compatible.
As a side note, if you just want to keep your phone, its easy to have the screens fixed/replace nowadays. And generally a cheaper option if your device is not under warranty.
This question has been asked and answered before, but I could not find the previous question thread, so I went ahead and answered it again. If you find the thread please don't downvote me, I searched for it, and even checked my history as I was the one who answered it before as well.
The only way to prevent this besides building a wall is by building more houses in the designated village area. Villages paths go out to the age of the area so that gives you a clue. But since you have 50 houses, villagers can no longer stay. this is because the village is, "Over crowded" so there is no other way you can do this.
Best Answer
In MineCraft, most mobs will refuse to drop down if the bottom is 4 blocks or lower down (the minimum requirement to fall damage with mobs), however they would happily drop down from three blocks, so make sure that there's not extra blocks or slabs sticking out just enough for the villager to willingly drop down.
However, a gate between the enchanting table room and the exit would be an easy way to make sure your villager stays safe from dropping and fall damage.