The build looks good and well thought out and it should work fine , the one recomendation that I would make is if you could up the watts on the psu to 550w or 600w just to be on the safe side with enough power to do what you want. Of course as long as it don't make you go over budget.
Yes that would be a good choice as long as your ok with what the price is and it doesn't put you over budget , which it looks like it would if that's the price you have put in your post. I guess if your ok with the cost then yes it would be a good choice of a power supply. I'm sure that the 500w would work that you listed but I tend to think in terms of having extra rather than not having enough and I have found that over time you can tend to add things to a computer and if what you add requires power then your power supply has to provide that extra power.