Hi black, great shots!
I'm afraid I can't help you with species, I know very little about African dragonflies, but I my thoughts on the genuses are:
1. Female
Orthetrum species (similar to European Orthetrum coerulescens)
2. Male
Orthetrum species (similar to European Orthetrum trinacria)
3. Female
Orthetrum species (Similar to European Orthetrum cancellatum)
4. Female
Trithemis species (Similar to Trithemis arteriosa)
I'm not suggesting the dragonflies in the brackets as identities, just trying to show where I'm coming from
Guy