1. Not sure about the anti malarials - you will certainly need something along the lines of Doxcycylin when in Mombasa. Nairobi and the Central Highlands present a much lower malaria risk. I generally divide time between Nairobi and the highlands (near Aberdares) and usually don't take anti malarials - no problems so far, but I do keep some doses ready in case of emergencies. If you are going to Mombasa, be guided by GP/travel clinic.

2. Get an insurance policy that has good medical cover, preferably with repatriation included. Medical care in Kenya can be very very costly.

3. Must-Haves: Camera!! Take a few changes of clothes with you and include something warm - fleece or something, as Kenya can be quite cold in August. Take basic washing stuff - shampoo's, soaps/showergel, toothpaste etc are readily available there, especially in Nairobi supermarkets. Films and digital memory cards are also easy to find in Nairobi. Mobile phone (unlocked) can be an asset, as coverage is extensive and SIM cards are cheap and readily available - Safaricom probably the best.

4. Backpack v's suitcase is a matter of personal preference. If you are planning on walking, or climbing while there, then backpack better. I use a 70 litre duffel bag as I have found that suitcases seem to get quite damaged. In Kenya, there is usually someone who will help you with your bags, so I find that weight and volume are more of an issue getting to the airport here.