The road from Maputo to South Africa (Via Komatipoort)is a toll road,excellent condition.Approx 1 hour travel to the border,border crossing can take a while.Entry to Kruger Park is approx 30 minutes from border-enter Kruger at Crocodile Bridge gate.The traffic police in Moz are a problem-they do stop travellers & try for bribes.I find them scary !!I live in South Africa & have travelled this route previously.It may be an option to take a bus or mini-bus taxi to Nelspruit 9or Komatipoort) to collect a car.I have not used public transport in this area but this will be cheaper than flying.
Enjoy your trip,interesting country,fantastic & cheap seafood !!
Let me know if I can provide more info.