Having spent several years on longhaul as a decidedly junior FO at one stage, I've seen quite a lot of Africa, including the delights of LUN (Lusaka for anyone who doesn't speak IATA). Great place FWIW.
...you cannot get shower water in your eyes...
... is no more of a problem in LUN as it is in LON. Having spent time in LAD (not to be confused with IAD as a few people did
), I can vouch for the fact that it wasn't a problem there either. Granted, I brushed my teeth with bottled water (good advice) but I can still see ok.
As for malaria tablets, you pays your money you takes your choice. Taking them for long-term use (including Malarone) can potentially cause more of a problem than getting malaria (non-BA medical advice).
PS: Never had Delhi belly either but then I never ate in the hotels.