I need some tips for photographing a military homecoming?

My friend has asked me to photograph her husbands military homecoming for her, since she will be too busy/distracted to get any photos. I'm excited!
I have a Nikon D3100 with a 18-55mm lens. Its new to me so I need some tips on what setting I should have it on, flash or no flash? It will be in a gymnasium. Some of the photos will be of her kids running to daddy, too. Any tips or advice will be greatly appreciated!

Get a good all round lens - 18-270mm then you have no problems needing to change it…

find a good vantage point… Find out about the route, then walk it… If you can speak to people in buildings that over look and see if you can get in there…

Your pop-up flash is good to MAYBE 15-20 feet. If there's not enough lighting, you will have to remain in flash range for all your shots. Try boosting the ISO to 800 or 1000, take some shots around the house and see if they look "Noisey". Use the widest aperture (smallest f#) you can and adjust exposure by setting the shutter speed. Keep the shutter speed above 1/60

Your lens has a fairly tight range. Get a feel for how close-far you can be.

Group shots with the backs of peoples heads should be the exception.

Shots that capture the emotion, faces first embrace/kisses.
Keep the shots intimate, tight on the subjects, a few crowd shots go a long way.

Get to the venue early and know where everything will be happening. Plan your movements and take some test shots.

Spare battery and memory cards?