HDTV and receiver audio connection problems [help]

OK, just purchased my first HDTV and I'm pretty thrilled to get it all set up.

However, I have a few questions first.

1. I purchased the TV as a refurb from Tigerdirect for $417 with a Mastercard. As I understand it, Mastercard doubles the standard warranty (90 days on refurbs). Is the Mastercard thing true? Is it worth getting an extended warranty? I know it can be on more expensive sets, but a 2 year is about $75 and 1 year $55. Should I go for it, or just hope that the 180 day warranty gets me through.

2. I also purchased an Onkyo HT-S5200 home theater (with the r570 receiver). It has HDMI, but does not pass through audio over HDMI. I am hoping to connect a Bluray player and computer as follows:

Bluray/computer >>>>[HDMI]>>>> TV >>>[Optical audio]>>>>> Receiver

Will this work well? Can the Vizio output surround sound from an HDMI source over its optical out? If not, how else might I connect them? The receiver has only 2 optical ins, but I have more than 2 devices that I want to connect, so I thought that going through the TV might be best.

Thank you very much for your assistance.