Two questions...

Is direct line of site to the receiver required for a remote, or does it work with radio waves?

If I want to control the light from a wall switch in addition to controlling the same light (and the fan) from a wireless remote, is there a way to wire it so that if the power is turned off from the wall switch, I can still turn on the light from the remote?

1. Most remotes are radio-frequency

2. The only way to do so, if I understand you correctly, is to get a matching wall switch with radio-frequency control.

http://www.ceiling-fans-n-more.com/ceiling-fan-remote-controls.php