hey kathy ya im new to the forum too. But I do know how to move ur music files from ur internal memory to ur sd card.
Connect ur DInc to ur computer. (Make sure the Dinc's driver is install so it can read it). Then on ur DInc slide the notification bar down nd click on the change USB connection type. Then tap on Disk Drive Mount and tap done. This should have mounted ur Dinc's Internal memory nd SD Card. Now on ur computer go to My Computer nd go to the section with removable storage is at nd open them up there should be 2, one for ur internal memory nd the other for ur sd card. Now u can just move the file like u would a flash drive.
I don't believe it "downloads" in the traditional sense. I think it's stored in "the cloud" and you just have access to it through Google Music. That's my understanding anyway. The point is to have access to 20,000 songs and NOT have them stored locally.
Once you have them in your Google Music library you can use 3rd party software to DL them to your computer. I use a Firefox plugin called DownloadHelper. I downloaded a Pearl Jam song to my PC. Seems the format is MPEG. Weird. You can then convert it to MP3 or whatever you want.
Someone who has used this service more might tell you more about it. I've played with it for maybe 10 min. I am uploading my entire iTunes library, which is going to take days, literally, to do. It's about 13,000 songs. I've been uploading for more than an hour and so far I've added only about 150 songs.