On the left as in the UK, Australia, Japan etc. Outlying roads are often in poor condition. Roads in the game parks are unsealed. Available in Nairobi, Mombasa, Malindi and at any coastal hotel. You can drive yourself or take a driver with you for a little extra cost.
Car hire is relatively expensive.
Some of the cars available are of poor quality. Ferries on Lake Victoria operate from Kisumu to Kendu Bay, Homa Bay and Asembo Bay. There are services on Lake Victoria between Homa Bay, Mfangano Island and Rusinga Island. From Mombasa, Malindi and Lamu you can take an Arab style dhow along the coast - unless specifically operated for tourists, there are no facilities on the dhows but it is a marvellous experience. Bikes can be hired in Nairobi.