No, photos are not really needed, though we do recommend sending 1 photo of you together, just in case.
Not sure about the scanning at the appointment vs. at home, since the scanning is a very new change, and I don't know much about how the new system works yet. Hopefully someone else can help with info on that.
Don't know about cost, either, I'm afraid. I've heard there are various charges for appointments, from no charge, up to about £800 for a premium appointment (24-hour decision), but don't know much about what each appointment type offers.