Yes, speaker cables are also included. Unfortunately i don't have any detailed information about the length. You might want to order some with it. For the S9700 i read a review that they are quiet short for any reasonable sized room and also very cheap. You can find speaker cables under accesories on the product page: Onkyo HT-S9800THX (7.1 Kanal, ohne Player)
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Oh, i forgot to mention. The S9700 is very similar. Actually the speakers look identical to me, just the receiver is a bit different. So that's why i would guess the cables might be the same that come along here.
That i don't know, i don't own the product myself. On the extra cables there are no connectors included. You might be able to re-use the ones from the included cables or you can also buy new ones, although those can be quiet expensive, just like the extra cable itself. Sorry i'm not very useful. This is still a fairly new product, so i have almost no information at hand, i'm still using the S9700THX as reference, which you might find some Unboxing Videos on Youtube. I haven't found one, where they actually unpack the cables.