If it is a Mack snow then it will produce snows if breed to a normal leo, about 50% of the clutch. That is 50% of the babies will be snow. If you breed a Mack snow to a Mack snow roughly 25% will be super snows, and look better than either Mack snow.
If it is a line breed snow and you breed it to a normal the babies will be somewhere between normal and the snow, but none would be similar to the original snow. If you get line breed snows you should only breed them with other line breed snows to produce good snow babies. Then hold back the best ones for future breeding to get better and better snows.
There are two different types of snows, and you should not buy them without knowing which you are getting. If you know which you are planning on getting it would be easier to answer your questions.