I've got a Minolta Maxxum 5000 w/ 24mm 2.8, 35-70 4, and a Vivitar 3700 flash. I'm leaning towards to 24mm, but what speed of film should I use, 100, 200 or 400 for best results? I can't really experiment too much.

-The 24mm may be a bad idea because it will most likely distort the people on the ends. I would be inclined to use the longest focal length you can and still fit everyone in.

The slowest speed film you can manage with your flash will give you the best quality (and least grain) for enlargements etc.

It might be best to not use the fluro lighting at all, as it's very difficult to color balance and will be inclined to turn skin tones greenish.

-You might want to get an FL-D filter to avoid the greenish look of fluorescent lighting. Your on camera flash, or small hot shoe mount flash will likely not work very well, giving uneven lighting. Your flash might not cover all the group equally, creating a hot spot in the middle, or darker edges (corners) in the resulting image.

Take a tripod, or find a stand to keep your camera steady. Take five or more photos, and hope that everyone's eyes are open, and everyone is sort of looking forward.

Use the longest lens that will allow all the people to fit into the photo, and still allow you to stand in the room. If that is only the 24 mm, have the people on the end stand slightly closer to the camera (one body width) to try to avoid some distortion. Anyway, you should be able to see any distortion through the viewfinder, but try to be perfectly parallel to the group.

If the lighting is somewhat low, you may be stuck with ISO 400 film. Since the composition of the image, and the interesting subjects, will be the emphasis of the photo, don't worry about ISO 400 being a little grainier film. The extra speed of the film should work under tough indoor lighting conditions, especially if you only have one chance to do it.