Good info Nemo.
I'd start with one, or all, of these power calculators if you haven't already.
http://www.northerntool.com/shop/tools/buyers-guides_wattage-calculatorhttp://www.briggsandstratton.com/us/en/generators/portable-generators/portable-generators-101/how-much-power-do-i-needhttp://powerequipment.honda.com/generators/wattage-calculatorThen decide if you really "need" it all or whether there are things you can work around for a few days or so. Like ac, a back up window unit to just cool a couple of rooms in the hottest part of the day or can you run window fans ? If you heat with wood, no need to figure heater. Like Nemo said, you could heat water outside, use an outhouse, etc. etc...
Then go shopping.
From what I know, if you're gonna run that 40 amps, you'll have to get a big unit, most portables are 20a or 30a plug ins and a bunch of 110. The picture of the Powerland shows a 40 and a 30. The 30's are usually four bladed and twist lock and that 40 will be four bladed flat like a dryer/stove/welder. You'll have to have a big enough cord to carry the amperage as well.
On the Powerland portable, that 10k is peak/surge for the extra power needed when refrigerators, air conditioners, and pumps cycle on. It's specs says 8k continuous and most fuel consumption data is based off a partial load rating.
Don't forget the cost for a transfer kit. They come in manual and automatic. You can save some coins going manual. Make sure it comes with a transfer cord, big enough, if your generator don't. The last thing you'll want to do in storm is be running six or eight extension cords. Make sure they're sized for the load.
Make sure it comes with wheels and handles. Big portables are over 200-250 pounds without fuel and are hard to move thru a yard, especially wet mud or snow. If you have a tractor or lawn tractor, you can mount it on a 3 point carry all or a small converted yard trailer. Then you can use it around your property for other things if needed. Not knowing the layout of your house, if you wire your house/well/sump separate, you could be moving this thing around some.
If you don't wanna move it, you'll need the coins to shell out for a cord large enough for the load. The power cord will need to be 8 ga. copper to carry 40 amps 10 feet. With power cords you want the juice coming out the same as it comes in, so you have to figure loss. Generally, as a rule, for every foot that current flows through a cord, there is a voltage loss. So a 50 ft cord loses twice as much power as a 25 ft. cord. To push 40 amps 15-20 feet, you'll need to have 6 ga., 30 feet, 4 ga. and anything longer, 2 ga. This will be a cost to consider.
Lastly, running a big generator requires a bigger motor. Electric start is nice, but you need to keep a spare battery. You may be able to pull one off now, but what about when you get older or injured shoulder. The Powerland shows a battery and keyed start.
Like Nemo posted links to, if you're gonna run "everything", you need to consider a standby, not a portable, JMHO. Set that bad boy on a pad, set an lp tank and pray for rain.
