Sorry guys for not check the site for a while.
I just got mio 3.3 tts installed on the device, TTS feature speaks the street name as "in 200 meters turn right onto Main Street".
To answer most of your questions. As soon as you got your device unlocked, the device is becoming a windows machine and think the SD card as a bootable usb disk. To leave the changes recoverable, I did not touch it's internal 2G Flash disk (where Pioneer software is installed), meaning, you need an SD card in the slot all the time for it to work.
Most of the applications (igo, mio) can be copied directly