Do you like to ski? = Fährst du gerne Schi? I ski. = Ich fahre Schi. I think there is no real difference between "Ski laufen" and "Ski fahren" but I prefer "fahren". By the way: You can write "Ski" or "Schi".

"Ski laufen" and "Ski fahren" are synonyms, however, "Ski fahren" is used more frequently. But as to word order, it must be "Fährst/Läufst Du gern Ski?" (there's inversion in yes/no-questions, i.e. the verb comes first) and "Ich fahre/laufe (gern) Ski" (the verb must be in the 2nd position) Hope this helps.