I have my plasma in a corner: my understanding is that the swfr is non-directional,does it matter whether it faces the corner or faces outwards?

Regards,
David

You really answered your own question. Since the subwoofer freq's below say 80hz are non-directional it makes no difference which way to point the driver.

Also, corner placement will give you the best output and excite all the bass nodes, however, this is not always the best location. You need to experiment with various places along each wall, or even on opposite walls/corners.

This is true, but sometimes minimal changes in placement can provide better response. So, simply rotating the box so the driver fires a different way may improve your sound. With all things audio, expirement and trust your ears.