Hi Anita! I think Arks has answered just about all your questions and has given good advice. So just to weigh in on the safety aspect - We have always felt safe in the reserve. We usually end up doing small walks in quiet places and love it. The most NB point - remember to respect the baboons. Do not carry food with you when you walk, and when you leave your car, ensure any food in the car is hidden from view. We have encountered baboons on our walks, and since we do not carry food, they ignore us. Also, recently all the baboon troops we have seen in the park, have been accompanied by a baboon monitor( a Parks employee who monitors the baboons and ensures they do not cause problems).
Some short walks that you might like to try:
1) Along the Olifantsbos road, +- 5 kms from the main tar road, there is a gravel road/pathway(only for bicycles and walkers) on the Cape Point side of the road - this can be a starting point to explore the fynbos and landscape and you can walk for a few minutes or hours(trail eventually ends up at Olifantsbos.)This trail is on the map you are given at the entrance gate - as a hiking path.
2) As Arks suggested - a ramble along the beaches at Olifantsbos. There is a designated footpath from the O car park, going towards Cape Point, which will take you to a wreck on the beach. Some of the trail is soft sand though.
3) Gifkommetjie - a few short footpaths thru fynbos taking you to some lookout points. (a few minutes to the lookouts).Very easy and short!
4) If you park at Booi se Skerm(near Black Rocks), you can walk along an old tar road(in the CT direction) to Venus Pool.When you get near the pool, you will have to climb/scramble down a few rocks to more closely investigate the tidal pool. I would estimate that it is a +- 2km round trip.
Arks spoke about terns - sightings at Bordjiesrif near the concrete tidal pool

and also at Olifantsbos.
Just to end - another nice drive is the road past Neptune's Diary to the Cape of Good Hope. This is quite a busy road, as tour buses use it, but there is a good chance of spotting whales(especially in Sep) and ostriches, also a chance of spotting a few eland(they like the escarpment above the Cape of Good Hope, but below the Cape Point car park - I believe HiltonP also spotted them in this area).
Hope this helps!