We have two, one in the backyard and one in front. I just make sure there is enough gravel or small stones in each so the butterflies can perch and drink. I find it easier to clean with gravel or small stones. I have an old colander that I dump the water/gravel into, rinse the gravel, swish out the container with a dish brush, and then put the gravel back in the shallow container with the appropriate amount of water.
Birds are going to come to drink, too, and do what birds doo-doo. Sand, I think, would be hard to clean so you'd be constantly replacing it.
Beer? Definitely not. Perhaps some people think the sugar content in beer is beneficial. NO, butterflies need water, and can get sugar from the nectar in flowers.
We have several varieties of butterflies (see my avatar) and they use the butterfly watering stations a LOT! Please don't use beer or other additives.