Hi Dave,
Great plan! If you are staying at the V&A Waterfront, there is so much within walking distance of there, a car can be a bit of a hindrance. I would arrange either to collect it from a downtown office (some are even in the V&A) or for the car to be dropped off at your hotel on the Friday morning so that you have it for the trips out of town and to the airport. If you don't want to self drive, there are several companies who will supply a car + driver for a number of hours or parts of a day. The licenced taxi drivers are not really permitted to be "engaged" by one fare all day, but many of them are quite happy to switch off their meter for a pre-negotiated sum of money. Speak with your hotel concierge - they would know of somebody and help you to agree a rate before you leave.
On Thursday, as far as getting to Table Mountain is concerned, a great tip is to use the "Hop On, Hop Off" bus tour. It starts/finishes at the Aquarium in the Waterfront and there are a couple of interlocking circular routes round town. You can buy your cable car tickets for the mountain on the bus so that when you stop at the mountain you will bypass the queue for the cable car tickets. City Sightseeing Cape Town | The Official Red Bus. Also whilst travelling on the bus, you can familiarise yourself on how things operate car-wise in preparation for collecting your car. Go up the mountain and enjoy one of the finest views anywhere then come down again and get off in town or maybe at Camps Bay for lunch. I hope this helps give you a few ideas.