I was a voly for years at the vineman triathlon events.

The key to running a successful aid statiion is to make sure you have plenty of fluids ready and in the cups for when the mass of runners come through. Ususally there is a median time that most people will run the distance in. You want to be prepared.
At some races the water/gatorade is in a big tub and you dip the cups in it and then set it on a table. Or you set up all the empty cups on the table and use a jug or pitcher to do a mass pour into the cups.
If there is ice in the water/gatorade make sure that it doesn't end up in the cups. Nothing like grabbing a cup of gatorade and going to down it only to choke on a chunk of ice.
When handing out fluids announce to the approaching runner what you have in your hand. Have your arm outstretched and be ready to run backwards a few steps as they grab the cup. This helps insure a smooth handoff.
Also hold the cup from the bottom so they can grab the middle of it.

As for people yelling at the volys. It happens. But then there are jerks everywhere these days. You will get many more "thank you for being here " than you will "there is ICE in this CUP!!! ".

Personally I think all of us who race should do our voly time. It's called giving back to the sport. It's a good thing.

Have fun!