Basically a good quality 500-550w unit can run any single graphcs card on the market while 650-950w can be required for Sli/Crossfire. Both the GTX460 and HD5770 are lower power cards. I would go with 500-550w for one and 650-750 for Sli/Crossfire. This gives you plenty of headroom for overclocking.
Stick with Corsair, Seasonic, PC Power and Cooling, Enermax ,Antec or XFX for the best stability and quality.
No they do not ship internationally I do not think. Stick with the brands I listed in the earlier post. I have no idea what the price will be but those are internationally known brands and top quality.
The EA500 ( if the sites specs are correct, 12V/17a = Seasonic ) is about 45% less the the EA500D Green nice deal
Oh, and it's enough power for either of the OP's graphics scenarios.
The 12V/17a [ if the specs are correct ] is actually dual rails with no OCP aka single rail, with 34 amps of output.
Even if the specs aren't correct and it's the first Delta model ( 12V/22a ) at around half the price of the Green model it's still a great deal, there's only a $2 difference at Newegg ( including shipping )
Not really. The graphics cards draws the most power and is generally what decides what power supply you need. The motherboard, processor ect. are included in the 550-650 watts or so you would need for that listed system.
Just stick with the brands I listed for top quality and stability. You do not want to buy a nice new system and put a "cheap" power supply in it.
If you can find it I would look for a Corsair 650TX. It will give you plenty of overclocking headroom and run 2 x 5770s just fine.