2) Personal item (second carry-on) has laptop, documents, point and shoot, etc.
3) Checked bag is a large MEC duffle bag (very little weight in the bag iteself) with tripods, heads, reflectors, chargers all padded with underwear, t-shirts, pants, etc!
Dust is always a problem for me on photo shoots and I expect it to be bad in the dry African savannah ecosystems. Dust is especially problematic for shooting video with tee 5D mark II.... it's a serious pain to remove dust spots from HD video! To save me the agony, I'm now using a product called Dust-Shield, which is an optical quality thin plastic film that seals the camera chamber and prevents dust from getting on the sensor. I just had my camera cleaned and put a fresh dust shield on... see next two photos. It works great and makes life so much easier!