The best approach is sniping, or just using the flame thrower to make it a quick battle. The more drawn out and complex the firefights, the worse it gets.
Speaking of cars and combat, it's pretty comical when someone comes ramming you out of the blue, and not in an armed jeep, but some cruddy compact. After going straight for you (does everyone in the game really hate me that much?), the driver gets out, stands still and say "huh?"
As for the malaria, it's another one of those botched ideas (along with the "realism" of digging out bullets, or using syrettes). It's not really a problem, but it feels like one of those ideas that probably sounded good to the team, was worked on for an hour, and then inserted into the game in raw form.
And yeah, nighttime is the best. I like the daytime too, though. Morning and dusk can kiss my ass.