A few things come to mind.
First, I don't think anybody can offer any advice about picture style without knowing your post-processing workflow.
If you're just going to be using consumer-level tools such as iMovie, then you want to get everything exactly the way you want it to look in the camera. If you like the way it looks on the back of the camera, that's the proper setting. If you don't like what you see, fiddle around until you're happy and then use that.
If you're going to be doing the post-processing yourself using more advanced tools, the same advice applies. You don't have enough experience and knowledge to properly make use of more advanced camera settings.
If somebody else is going to be doing the post-processing, ask that person to set up the camera for you.
Next...cinematography is a hugely complicated skill. If this is the first movie you've ever shot, accept right now that you're going to screw things up, and don't beat yourself up over the fact that you will. And make sure that nobody is relying on you to get everything right the first time.
Here's enough to keep yourself from hurting yourself too badly:
1. Shoot manual exposure. Either use 24 FPS and 1/50 second if you want a film-like presentation, or 30 FPS and 1/60 second if you want more of a TV-like presentation. Set the aperture for your desired depth of field. Then, get the proper exposure ideally by adjusting the lighting of the scene, by using neutral density filters (a variable filter is especially handy) if that's not practical, and lastly by adjusting your ISO. Whatever exposure you go with, you'll very much want to stick with it through the entire scene. The pros use expensive meters to get the light right, and their insanely-expensive lenses are calibrated in T-stops to let them do so. You're better off just putting the camera's built-in meter in evaluative mode and trusting what it says. Point the camera everywhere you will when you're shooting, and pick the least-worst compromise for your manual exposure.
2. Use a custom (manual) white balance. See the camera's manual if you don't know how to do this. If you don't, unless you've got superb lighting, your movie will have a distracting color cast to it.
3. Use a tripod. The cheapest video tripod you can get at your big-box electronics store will be horribly inadequate and a thousand times better than hand-holding.
3a. If you must hand-hold and you don't have a Steadycam rig (and somebody who knows what to do with it), use a lens with image stabilization. The results won't quite look like the Blair Witch Project that way.
4. You're going to have to use manual focus, no matter what. "Pulling" focus for video is a special talent all unto itself, and ideally performed by somebody other than the person operating (aiming) the camera, generally by watching an external monitor and by knowing exactly where to physically turn the ring to based on where the subject is on the stage. "Good luck with that," as they say. If there's any doubt, go with the smallest aperture you can live with to get the most depth of field, and then see #1 above again. If there's nothing distracting on the set that you need to mask with out-of-focus blur and if you've got enough light, pick a hyperfocal-style combination of aperture and focus distance that will cover the entire stage, and then tape down the focus ring.
5. Record audio externally. If you were planning on using the camera's built-in microphone, get a Zoom H-series recorder and use it instead. Just put it on a mic stand next to the camera, and be sure the stand doesn't get bumped. You can use the recorder's auto-levels feature to figure out what the "good enough" audio level is, but then turn the feature off and manually set the audio level for the actual shoot. Changing audio levels during a shoot is as bad as changing exposure. Just let the audio run during the entire shoot. You can sync the audio afterwards very easily if you use a clapboard, and almost as easily if you just have a person on camera clap hands.
6. Practice, practice, practice. Do the above and you're probably not going to embarrass yourself too badly, maybe, but you're obviously not going to win any Academy Awards. The more you practice, the less your chances for embarrassment. Practice enough and you'll get past the danger of embarrassment and towards the possibility of actually doing something with merit.