Airlines · Namibia

Hi everyone, I'm heading to Namibia next May. I'm planning to take a first flight from Paris to Johannesburg with Air France, departing at 11:20 PM and arriving at 11:05 AM in Johannesburg. Then a second flight from Johannesburg to Windhoek at 3:25 PM with South African Airways. Four hours between the two flights seems enough to catch my connection, but a friend told me I should maybe take the 5:30 PM flight instead because I need to go through immigration, collect my luggage, and check in again. Apparently, I have to do this because I bought the two tickets separately (it's actually much cheaper). What do you think? Also, in terms of South African airlines, which one do you think is the most reliable between South African Airways and Airlink? Thanks for your advice!!