Got my LOI and Agency Registration certificate this morning - as soon as i'd paid by paypal.
You just need passport number, name, name of Pakistan Embassy, start and end dates.
Tour Agency Registration is just a government issued certificate for the tour agency. Not all countries ask for this, ie Asian countries, but they do in the UK. I got a Pak visa in Bangkok a few years ago and I didn't need this - but the guy in the consulate was really unreasonable and they nearly tried to get me a PIA airticket.