Can't help with speed settings - the mitre saws I've owned never had any. :?
As for tearout - some is inevitable on the underside and the fence side edge of the board because of the direction on blade travel.
I think I'm right in thinking the 712 is a slide saw, in which case you can eliminate tearout on the underside by drawing the blade lightly over the top edge to score it, then plunge down in front of the timber, then push through to complete the cut.
Although it works - I don't recommend scoring your cuts with a knife or chisel. You'll forever be scoring wood on most projects! and if you miss the score line by even a little, you may get tearout. Also, your score line may not be perfectly straight and square leaving you with a messy cut in a different way.
To eliminate tearout on the fence side edge, you will need to make an auxillary fence in MDF or similar, and attach it to the metal fence. This will "back up" your work at 90º and also give you a kerf for exactly where the blade will cut, which is useful for alignment. You may also be able to get 45º cuts out of this asa well, but if you use other angles much, best to remove the aux fence or you risk widening the 90º kerf and so introducing more tearout.
Steve said to take things slowly - I don't exactly disagree, but the right speed is fairly quick and going too slow introduces new problems. Experiment with different speeds to get a feel for what's right.
Make sure you use a good sharp blade with around 60 teeth for cross cutting smaller stock. Around 40 teeth for larger stock.
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