Nerdsniped: You're describing a IEC 60320 C13 cable - they're technically only spec'd for 10A, which means you're looking at ~1200W, not 1800.
(However, UL will list them for the full 15A -> 1800W, and I'm sure plenty carry that. And for that matter, I suppose you can get twice that in Europe on 240v...)
2. Powerline networking is considerably slower and less reliable than CAT5/6. Additionally, building code for running power lines is much more strict than low voltage CAT5/6