Is the external micro SD card path the same for all devices? I am using a Samsung Tab 2.

There is a path: /mnt/external_sdcard/myfile. Here, I can save, read, or write my file to the external micro SD card.

I'm just wondering if this path is the same for all devices, or if it may be different.
Simple answer: No.

On my device (LG P990 Optimus 2X) the path changed after upgrading from 2.3 to 4.0. Currently the path on my device is /mnt/sdcard/external_sd.

So this is highly dependent on the device provider or on the version.