I think it's going to be a lot easier if you can actually be in Malawi when you do it. I just bought a hectare of lakeshore land up north near Nkhata Bay. Firstly, I identified the land, then found the local chief. Next I went to the LANDS Office and got confirmation that they did own the land. They then did a survey and a map and gave me the relevant paper work (this cost 183.000 kwatcha in total) for the chief and myself to sign.
Took a week in total although as I'm not Malawian I can't buy the freehold but a 99 year lease.
Hope this helps.