I have a few of questions about the medicines that I hope some people can answer:

1) When it says "one drop every half hour until cured", is that a real-time clock, or a fishy clock? i.e. if you run at 2x speed, should you only wait 15 minutes, or if 1/2 speed wait an hour?
2) What happens if you don't wait the full 30 minutes? Does it not take effect, or just not at full strenght?
3) Likewise, if you wait much longer than the 1/2 hour?
4) Is dropping medicine in a tank without any sick fish harmful, or does it help prevent sickness?
5) Is there a problem (when there are both types of sick fish in a tank) to drop one medicine and then immediately buy the other and drop that?