There is no option to listen to lossless music, even if that is what the user has uploaded. The highest quality is 320kbps MP3s. If a lossless track has been uploaded and the user then downloads the track at a later date the file will also only be a 320kbps MP3.
Artist information is downloaded from Last.FM in order to show extra information on the playing artists such as bios and pictures. This way the user does not need to leave the app if they are interested in extra information on who is playing.