I only clean rotors after i re-install wheel or did some other activity that made me touch the rotor or got it possibly contaminated. For example when i service my hubs I fiddle with grease hands and may contaminate the rotors. After such work i always clean them.
I use up an old can of brake cleaner, but will switch to mineral spirits once that is used up. No need to clean pads, also no use. Pads need to be replaced after contamination.
I don't think alcohol is suitable since it is polar (like water) and doesn't dissolve non-polar things like oil and grease.

Don't sweat it, cars have been driving on disc brakes exposed to saltwater etc. and no one is cleaning them. Bike rotors are more exposed, though. But motor bikes also work fine and I doubt Hell's angels spend a lot of time cleaning rotors.