1000W is enough but that isn't the big deal with the 295X2. The issue is how many amps are on your 12V rail. It is better to go with a single rail PSU because that way you don't have to worry what PCIE power connectors are on which one in a multirail PSU. 83.2A on the 12V rail should be enough.
You don't need a 1000w power supply for a 295x2, you just need a power supply that can deliver 28A on each of the 8 pin PCI-E connectors. Most high quality 850W power supplies should do the trick (the draw of the card is about 600W on its own) but if you want the 1000W go ahead it will work fine
Well i dont know much about powersupplys but thats the EVGA power supply i have and im not sure if it has one or two rails. Ive been around PC parts a long time but not power supplys. Last time i researched power supplys was 4 years ago.