What size cord goes with this set, can i use the regular cord with these?

The set comes with three SWIV360 cables (two of the 6 inch and one 8 inch cable). All ChiaoGoo large size cables fit these tips.

Is there a way to make 16" circulars with this set? (Is there a 10" cable available separately? I don't see that anywhere.

Using the 8" cable with the two 3"needles, will give you a 14" cable, which in my opinion is more versatile than 16" circulars. You can knit a smaller diameter without stretching out the stitches.

I heard that model 7230 is fake is this true?

No, it is not true! ChiaoGoo controls its brand on Amazon and monitors its authorized Amazon sellers closely. ChiaoGoo also has MAP in place, so that sellers cannot go below a certain price. Just beware of any sellers with only a few reviews selling only a few units of the ChiaoGoo sets below the price of the bigger sellers.

Are there other size cords that can also be used eith this set?

Yes, ChiaoGoo size L cables come in 14", 22", 30", 37" and 50" in both the Swiv360 (7714-L. 7722-L etc) and the regular non-swivel Twist cables (7514-L, 7522-L etc).