I listed, as you have done, the most important items and checked the power requirements in watts of each. Some electrical items can take 2 or 3 times the rated power requirements to start up. I came up with a Honda ECM 2800 generator. I bought a petrol genny but in hindsight maybe I should have gone for diesel as it's legitimate (or was) to run a generator on red diesel which is much cheaper than petrol.
Here's the tricky bit: how are you going to get the power into the house? I got my local electrician to install a waterproof plug on the outside wall of the house and lead a cable through the wall to a man-size switch by the electricty meter. I then got my electricity company to cut the main power cable on the house side of the meter but before the circuit breaker board, and connect the aforesaid new cable and the main cable into it. (Breaking the cable on the house side of the meter is so you don't pay them for the electricty you generate!) This way when I want to use the gen (which I do occasionally to make sure it still works) you can do so by isolating the house from the mains by flipping the switch. I also had small circuit/light put in the switch box so I could see whether there's a mains supply or not so I know when the power is cut, when it returns without having to flip the switch back and forwards.
Having the house isolated is also useful when there is a power cut and the electricity guys are trying to mend the cable somewhere. They can't do this if your generator is keeping the line live. Maybe your local electricity company will have some guidelines on installing gennies on a website somewhere?
The genny is in an outhouse and when it's needed I run a beefy cable from it to the plug on the outside wall. You get a voltage loss on long cables so you want a meaty one if it's any length - and anyway, you want to max out the power you get having generated it with expensive fuel!
I have heard of people powering the house by plugging the genny into a regular wall plug but I'm not sure of the veracity or safety of this.