Intercom installation questions....?

I am installing a musci/communication system throughout my home, I have finished wiring the lower level (CAT 5E) and have since networked it up into the attic. I will begin to fish the cables down the bedroom walls. Any pointers on fishing to make it as painless as possible? Also, I will need to run power to the two transformers of the system (one for the CD changer and another for the intercom itself). I have no outlet nearby, only a light switch. I think that will be my biggest challenge. Appreciate any pointers you can give me. Thanks.