LOI - Australia has two of the more open minded and easier to deal with embassies, ACT and Sydney. They accept letters of invitation from tour companies and friends. They have also on occasion accepted applications without a letter of invitation where the applicant has had sepcial circumstances and written their own letter explaining their situation. We do not recommend asking any random Pakistani to be your "friend" for the purposes of getting an LOI. There are very real security obligations and responsibilities that go with inviting someone to Pakistan. This is the reason why we always suggest that unless you know the person well it is best to go through a professional company.
Applications can be posted in and you should include a registered post reply paid envelope for the return of your passport.
Processing time - 5 days to 2 weeks.