1) Olympus Zuiko 70 - 300mm F/4 - 5.6 lens
This would be good for taking pictures of things far away with good light. It would be useful on the safari ride, taking closeup pictures of the animals on the walking tours, taking closeup pictures of friends that are on rides (while you are not on the ride). It magnifies distant objects well, but it requires relatively good light to work. It would not work well for indoor shots.
2) Olympus Zuiko 50mm F/2 lens
On your camera, it will also magnify things somewhat. Basically, if you zoom in as far as possible with your current lens, that is about how this lens will look. The big difference is that this lens lets in much more light. You can can better pictures inside or at night with this lens. Also, it can take pictures with the subject in focus but the background very blurry so that it doesn't distract you from the subject. This lens on your camera is a pretty good match for what is considered an ideal portrait lens on a film camera - somewhat zoomed in, but not too zoomed in.
Also, with this lens, you can't zoom in or out but it will take better looking pictures than a lens that does zoom. It's a tradeoff - the more a lens lets you zoom in and out, the more compromises to picture quality the lens maker has to make. Lenses that don't zoom at all generally have the best picture quality.
3) Sigma 30mm F/1.4 lens
This lens is similar to the 50mm lens. It's less zoomed in (somewhere between the middle and fully zoomed in on your kit lens). It also has a lower f-number, so it can take pictures in even less light. This would be a great lens for taking pictures of dark things like the light parade or on dark rides.
Which is the best for you? That depends on what you want to shoot.