I don't think plugging your speakers into the wall would be a problem as the electricity would only be used to charge the stators and run the bass amp. The musical signal comes from your amp. I would try them both ways to see if one way sounded better though.
Considerations for positioning include distance from front wall and side walls, and your distance from the speakers, which should be a little further than the distance between the speakers.
How are you going to set them up in your 11' X 15' room? On which wall, etc. With a little more information we could probably help you more.
Those are nice speakers. Enjoy them!