On windows based computers when you plug in your phone it should give you the option to enter the device as a hard drive and pull the pics off. I don't PW lock my phones so not sure if that affects it but I don't see why it would. Give it a shot.
Nope. Apple isn't stupid. You can't pull pics off in Explorer until you enter the passcode and the phone is unlocked either. Maybe if it's a computer you used while the phone was unlocked in the past.
Good for Apple to do this so creepers can't just take someone's password protected iPhone and just look at their pictures. OP
If you have the computer that you backed up with before then you can do a backup again. That way you won't lose anything. A computer that did not backup the phone before would be stopped by the passcode.