> Environment.getExternalStorageState() returns path to internal SD mount point like «/mnt/sdcard»
No, Environment.getExternalStorageDirectory() refers to whatever the device manufacturer considered to be «external storage». On some devices, this is removable media, like an SD card. On some devices, this is a portion of on-device flash. Here, «external storage» means «the stuff accessible via USB Mass Storage mode when mounted on a host machine», at least for Android 1.x and 2.x.
If a device manufacturer has elected to have external storage be on-board flash and also has an SD card, you will need to contact that manufacturer to determine whether or not you can use the SD card (not guaranteed) and what the rules are for using it, such as what path to use for it.
Son, I am disappoint.