1) either a phone is unlocked or it isn't, there's no in-between
If you can use any SIMs in it, use any network, then it is unlocked.
2) just plug it in the computer via a micro-USB and the phone will have a "USB mode" button on the screen that you press, and once done, you'll have to phone show in your explorer as if it's a jump drive... just save/copy files over. Music can be done via music players (synch) such a the simple Windows media player. For images, they'll be in the DC (camera) folder.
NOTE: if you install Preware (highly recommended), you can get WIFI file sharing that does the same but via WIFI, so no cables needed, your phone becomes part of the network and available in explorer as another computer and you can access the files/folders.
3) if you're on WIFI, simply open the catalog app, nothing difficult or required.
if you can't do any of these things, them the phone is NOT unlocked, it's been put in DEV mode only.
To unlock, you'd simply need to get an unlock code...
I used this service for my Pre2: DigitalUnlock: Unlock your Palm Pre
Worked fine, just follow the instructions.