I'll attempt some answers to some of the questions, but am open to correction.
Firstly, being a large government organisation, the SAAF can not have a pilots course that aren't somewhat representative. So, although it is not true that "a white male has no chance of getting selected" as some would like to let you believe, if you sit with 80% applicants of a minority race group, some of the possibly successful candidates in that group might be replaced by good candidates from another demographic.
To answer your questions about flying hours and pay, I'll point out some critical differences between civilian world and the SAAF. Most importantly, the SAAF works on a budget as determined by government, while civilian companies' (or individuals') income is dependant on how much work they do. Therefore, if the defense force is struggling with the budget, some of the non-essential flying of the SAAF may be cut. Therefore pilots of aircraft like C130, Oryx, BBJ will rarely complain about hours (unless it is about too much flying from time to time). In contrast, as long as the contracts are good, pilots for civilian companies fly many more hours (often up to the maximum allowed by CAA per month / per year). If however the contracts expire (as happened during the recent recession), civilian companies can't keep pilots if the don't fly enough. Job security in the SAAF is therefore much more than for civilian pilots. Even if you fly 0 hrs in the SAAF, you will still get paid at the end of the month.
Now, regarding pay, the average pay in civilian sector stays higher than for the SAAF counterpart. Whether it is "enough" or not, is really up to yourself, but if money is a large consideration, I would rather suggest you follow your chosen career path as per your university studies and stay out of aviation alltogether. If you want to get into aviation for the love of flying, my personal suggestion would be to try the SAAF. The flying is much more rewarding (again, I stress this as my personal opinion), and there are some very dodgy jobs out there in civvie street, especially for junior pilots. 16 years sound like a long time when you're 20, but ask any 35 year old how quickly it goes past. If you choose to leave the SAAF at this stage, you should be in a good position to accept some "less dodgy" jobs in civilian sector. That is of course if jobs are available at that stage, depending on the global financial situation. If not, at least you are assured of a salary come next month.
Lastly, the number of pilots needed for each of the 3 lines, vary from year to year. Your personal choice does carry some weight and it is in the SAAF's best interest to place you in the line that you are most suited to (personality types of pilots in the different lines differ vastly).
Now final lastly, and most importantly: As Roger mentioned, military aviation takes a lot of commitment. There are lots to complain about in the SAAF, but to a certain number of people the benefits of flying for the SAAF far outweighs the problems. A crude test for whether you are one of these people is that if you don't already know most of these randomly chosen concepts: SAM, BVR, HUD, Casevac, CAS, Indirect Fire, C&C, LTKGIH, you might not find military flying as fulfilling.