Thank you for your question on the wattage rating for when you loose power.
You can take all the amperage readings off the model numbers of the appliances and multiply it by 120 (volts) to get a high but close estimate of the wattage of generator you will need for a power outage.
Of course the larger the generator the more electricity you will have available.
A portable power generator will need to have a running wattage of between 5,000 and 7,000 watts to run the bare necessities of an average home.
This would include a Frost free refrigerator and a frost freezer storage freezer. You could also run a few lights and a 1500 wattage space heater.
These will require that you have a standby fuel source of 20+ gallons of gasoline. Because if you do not have power the gas stations will not either in most cases. So you will need to have some 5 gals containers that you can fill quickly so you have some place to put a fuel reserve when need it.
I recommend the roll about transfer containers.
We sell a 5,000 wattage generator model that may meet you needs | sears.com/briggs-stratton-5000-watt-portable-generator/p-07133147000P?prdNo=3&blockNo=3&blockType=G3&blockNo=3&blockType=G3&MML=MMLxexpertxmerch
Here is a Briggs and Stratton wattage work sheet for you to see what you need.
I hope this information will help you.