My limited experience has all been trial and error, although I have not experienced any real mishaps.
The main adjustment I have had to play with is to angle the feeder in towards the fence adequately.
The Scheppach feeder (on Scheppach spindle moulder) I have has adjustable speeds, but I have just left it on the setting it came with - it seems pretty fast, which is fine once you have the thing set up right!
I do always use a sacrificial fence with the cutter advanced through it - the aluminium fence that comes with the machine leaves a wide gap that I was concerned could catch the leading edge of the workpiece which would not be good with a power feed.
Cheers