Newegg does not warranty the products they sell. They offer a return service that is normally 30 days. For the holiday season, they've doubled that to 60 days. If a product you purchase fails within 60 days of the purchase date, you can return it to Newegg for a replacement (see specific return policies). Beyond 60 days, but within the manufacter's warranty period, you'll need to contact the manufacturer for repair/replacement.
Yes. It looks like that motherboard comes with two SATA cables.
I've dealt with only Newegg and they are great, whereas I have known at least three people that have tried buying a pc at cyber and their experience was horrible at best. One guy actually paid for his system and didn't get it for eight yes, 8 months after order for a various amount of delay reasons, and because he had paid with a cashiers check he was having a terrible time trying to cancel. Others have not been happy with their builds as they didn't always have what was offered, and major brand in the listing doesn't always mean quality. Just my two and a half cents.