Turning the power down reduces the flashes output. Multiple flash units will help get more light on the subject. To do this you set your flash on automatic and take a piece of white paper and fold a portion of the flashes output directly back into its sensor. I have been told, that you can use a small piece of fiber optic cable to do the same thing, although I personally have not tried it. This is purely an aesthetic preference.
Frozen pictures tend to look fake, a little blur adds some realism to the shot.
Again, this is an individual thing and you have to play with what you got and find out if it gives you satisfactory results for your tastes. The second reason to do this type of photography is that strobes have little to no propagation delay. They do not have mechanical things to move like a shutter and their reaction times are typical less than a millionth of a second. This will be recorded on the film as image blur. To have it travel 14.4 inches across your picture while the shutter is open will not return desirable results.