Meg lehet-e azt oldani, hogy amit a Google Playből töltök le alkalmazás, az az SD-kártyámra jöjjön le egyből?

Ehez custom rom/kernel kell. és minden eddigi adatod elveszik a telefonról

Viszont ha ezt megcsinálod alapból az sd re telepítődnek az appok. Még az is ami nem áthelyezhető

This is the way to have /data on the SD Card directory:

Copy all /data to the SD card directory: /mnt/sdcard/data

Delete /data

Create a symlink that points to the SD: ln -s /mnt/sdcard/data /data

The main problem is that /data could be EXT2/3/4 partition, while the SD Card is FAT32. The best thing to achieve what you want is to create an extra partition on the SD Card as EXT2/3/4 filesystem. Then you can link the directory /data with the partition.

When the phone restarts, it will mount the data partition more or less like this:

mount <args> /dev/block/mmcblk0p2 /data

Since /data is pointing now to /mnt/sdcard/data, the above command is equivalent to this one:

mount <args> /dev/block/mmcblk0p2 /mnt/sdcard/data

So in the end, we would have our data partition mounted in the SD card. Again, it should be in a separate partition, so we have the SD card as FAT and the extra partition as EXT2/3/4 so it won't fail when it mounts due to the filesystem.

If you want a more elegant solution, you can try any of the XDA Developers App2SD scripts, they let you achieve the same but without symlinking (it will mount it and bind it to /data). You will only need a Custom Recovery to be able to flash them. You can check them here.