Yes. The Seasonic is great. The XFX is also great. You won't go wrong with either. If you plan on OC'ing either the card or the FX-8350, you will want the best 600W+ PSU you can get. You won't want the Evga 600W if you OC.
Yes, you are good. PCI Express is backward compatible, if that was your concern. But be sure you have a high quality PSU 600W or better w/2 x 6+2 pin connectors.
Nothing I would recommend for a $600 gfx card. Besides, you're spending big bucks on a card and you can't spend more than $40 on the PSU that powers it? This is the only sub-$50 PSU I'd suggest (but not recommend) for that card: http://www.newegg.com/Product/Product.aspx?Item=N82E16817438014
Nothing I would recommend for a $600 gfx card. Besides, you're spending big bucks on a card and you can't spend more than $40 on the PSU that powers it? This is the only sub-$50 PSU I'd suggest (but not recommend) for that card: http://www.newegg.com/Product/Product.aspx?Item=N82E16817438014
Gold, silver, bronze are simply efficiency levels. Power factor ratings. How well the PSU converts your electrical power at the socket to usable energy at the PC, and how much is simply wasted. It has no bearing on quality, except indirectly.
Yes. The Seasonic is great. The XFX is also great. You won't go wrong with either. If you plan on OC'ing either the card or the FX-8350, you will want the best 600W+ PSU you can get. You won't want the Evga 600W if you OC.