Any question answered...

Yes. Unless you're doing a PA for a club or something like that then you're not going to need anything larger than standard lamp cord. If you try then you'll melt the cable and the sound will be shite as the conductivity will be poor.

With PCs you want to keep the data cable away from the power cable. It can cause fuzzy lines across your screen or blurriness.

Interesting comment about power interferance.