Yes, but I've never bought games from there. Can you buy multiple games from it at a time?
No, not really. Just one after the other. But there's a similar mechanic: Download in Standby Mode. You can browse for more games, add them to the downloads list, and when you're done, quit the e-Shop and close your 3DS. It will then download all chosen titles simultaneously, and I even think it's faster than the immediate download.
"Evil, beware. We have waffles..." - Raven, Teen Titans