recomm on Moz
just follow the coast line in Mozambique, I would say. It might be nice to know that there is a new bridge to Tanzania. Not sure whether you get your visa at this borderpost.
In addition to the beautiful beaches along the coast line, I enjoyed Beira for a short stay. It is not exactly on the route, so you have to take a detour from the mainroad going north. Furthermore, the NP Bazaruto Islands are worthwhile, opposite to Vilanculos.
Also please be aware that the main border post at Komatipoort into Moz only issues very expensive visa. An alternative might be to go through Swasiland and get your visa for $25.
Fuel gets a bit more expensive the further you get from Maputo, but in Beira it is cheap again. And from there onwards, the prices increase again.
Enjoy Mozambique man!