Why does it say add water at 164.9, then list a step temp of 150?
The program has determined that mixing this amount 165 degree water (12.63 qts) with your room temperature grain (10.10 lbs) will drop the strike water temperature from 165 degrees to 150 degrees.
Why does this say heat to 168, but list no water?
The type of mash you've chosen is a temperature mash. This means that you are using a direct temperature source, like a burner or heat stick, to bring up your temperature. If you want to use water to bring up your mash temp, you'd need to choose a Double or Triple Infusion. Or you could remove a portion of the mash, heat it up, and return it to the main mash to bring the temperature up. This is called Decoction, and you would use that option in the drop down menu.
What is the step time?
It's the amount of time you will be holding your mash at that particular temperature.
Style Vols?
This is the amount of carbonation (in volumes) that your chosen style of beer typically has in it.
Carbonation Volumes?
This is the amount of carbonation (in volumes) that your particular beer should have in it, providing you use the parameters supplied by the program. In this case, if your beer is 60 degrees F, and you push 21.64 PSI of CO2 into the headspace and keep it there until the beer reaches equilibrium, you will have 2.4 volumes of CO2 in solution in your beer. Looking at the style vols ( 2.0-2.8 ) you can see that this is within range for the beer style you have chosen.
Cheers,
Dave