I haven’t tried to buy anything in RB2, but AFAIK in Beatles the only way to buy anything is by individual track. It’s a pain in the balls, especially if you’re saving the songs to the SD card, since you have to click it, wait for it to download (which takes a minute or two for me), then click for it to transfer to the card (which takes another minute or two).
You also can’t buy the albums as a whole, which also means you can’t do the whole Abbey Road medley without stopping to load.
Why the hell have they made it so complicated on the Wii? I’m sure a lot of people who intended to download a full album got frustrated and ended up not getting several songs.
You can manage the list by hitting the minus button. That will resort by genre, artist, year, or difficulty I think, so if there are particular styles you’re interested, it’s easier to find them. Also, if you hold down the yellow button on the guitar controller, it gives you a table of contents so you can go directly to the band or genre you want.