Rhodesia was a war of small actions. Other than the bigger cross-border raids, even 'platoon actions' were quite rare until the last two years of the conflict. Portuguese operations in Guinea involved battalions and companies, while again in Angola/Mozambique actions tended to be much smaller. Post-Portugal both Angola & Mozambique commonly saw much larger actions.
I'm guessing that Rhodesia will be the focus of your interest, as the 'Portuguese' part of the range haven't been fully developed as yet.
Paul L. Moorcraft and Peter McLaughlin - 'The Rhodesian War' is still the basic go-to book for a general history and unit details etc. If you are buying just one book, this will do the job.
For my money any of the 'Africa @War' books by
30° South/Helion (also available on Amazon etc) are great, packed with info and anecdotal material in an 'Osprey' style format (albeit with much more content, but no pretty art); bear in mind though that some of the authors have varying degrees of bias.
If you are interested in Angola/Mozambique too... then John P. Cann is the guy to look out for. He's wrote one of the Africa@War series, but also has worked on some of his own titles. I haven't read the ones on Air Ops, or the 'Brown Water Navy', but the more general one on the 'Portuguese Way of War' was very good.