Another way to mute the organ is to hit the low C presets on both manuals. Just be sure and to hit the desired preset when you go to play again.
Slow and fast designate how fast the leslie turns in the cabinet. If you can see the cabinet from the organ you should be able to see the horn spinning around and changing speeds. If it is hidden somewhere like most churches do so they can mic it, then turn it to fast and then go look at the leslie. You should also be able to hear a difference in the sound if you hold down a note or a chord turning the leslie from fast to slow, and this is a neat effect that you can use when you're playing.
Some Leslies have the ability to stop the speaker all together, in that case ensemble might be another name for the Leslie at slow speed. But then again, some organs have ensemble as a designation for chorus.
When I 1st started playing my leg hurt, but just keep playing, you'll get the strength you need, make sure you are relaxed when you are playing.
I don't consider organ easier or harder than piano, but I think it is very important to consider the two as 2 seperate instruments, just as someone suggested. If you're used to playing piano, you're used to a relatively harder action than piano, it's easy to fumble keys. I've practiced scales with a metronome to overcome this. Rhythm as an organist is important, because you kind of have to think like a bassist and a pianist all at the same time. At the same time, you don't want to think as a bassist or a pianist, you want to think like an organist.
