Reheating rice for 25 guests
When making rice for a large group, you should take a hint from the restaurants and do it in the oven in a large roaster or baking pan.  Put the rice in a pan, add boiling water and salt, and then cover with foil.  Or you can make it like a very large pilaf which will make it more special.  But oven in large pan is the way to go and make it fresh.

I don't have amounts because you will know how much you need to make. Common knowledge is 2 times as much water as the rice, and common knowledge is, generally, too much water, particularly in large batches.  

Again, a restaurant recipe will do you well.