Full system wipe.??

[RASH]

I have recently flashed dark knight ics rom.. On some occasions i get force close errors & random soft reboots..
I want to do a full wipe, both system & data.
1. In recovery select factory reset
2. wipe cache
3. wipe dalvik cache
4. format system
5. format data
6. format cache

Question DOES FULL WIPE DELETE MY PHOTOS, MUSIC, VIDEOS, APP APK'S FROM INTERNAL SD CARD/MEMORY....??


If I swap nandroid backups (different roms for different firmwares) every other week ..
Will I cause any damage to the phone or is not good idea..??