Hi,
I think a 750watt will be more than plenty. Have a look here (or any other PSU calculator you can find) punch in your details and you'll see you could get away with less than that.
I use a Corsair VX series PSU (450watt) and would buy another Corsair without hesitation. It pays to buy a decent brand I think. Others may have their favourites but I chose the Corsair after reading plenty of reviews.
I don't use a UPS (toyed with the idea plenty of times tho) but I'd buy an APC if I was in the market for one.
Hope this helps.
Ian.