Yes, that's a common method of inserting tiny icons on web pages. CSS is used to select the correct icon. The total image you're talking about is "only" 65k, so relatively speaking not too much of a hit on bandwidth. It's assumed that users are going to see many of the icons anyway, and there's a small overhead for every individual request, so sending the whole icon sheet at once might actually use less data.
Yes, that's a common method of inserting tiny icons on web pages. CSS is used to select the correct icon. The total image you're talking about is "only" 65k, so relatively speaking not too much of a hit on bandwidth. It's assumed that users are going to see many of the icons anyway, and there's a small overhead for every individual request, so sending the whole icon sheet at once might actually use less data.