It is actually 100 Amps @ 120 VAC. I think you dropped a zero somewhere. In reality, it is more likely 50 Amps @ 240 VAC.
We have a generator this size for our 4000 sq. ft. house in rural Oregon, and it is quite enough for us.
We have to recognize that the generator is to alleviate an emergency situation, not to make us independent from the power grid.
It is more than enough to run our refrigerator, freezer, lights, garage door openers, internet, TV, microwave, computers and all kinds of small appliances. What represents a large load and probably should be postponed until power is restored is the electric oven and the clothes drier. We have a heat pump and the generator is too small to run that, but we can easily make do with one or two space heaters and a propane fireplace. We have a gas cooktop so there is no danger of starvation, but you can probably run an electric cooktop if that is what you have. Try not to use all the burners at once.
As soon as the generator comes on, move at least one car out of the garage -- you do not want to be trapped if something goes wrong.
You should be able to pull the emergency release and open the garage door manually. The spring boost means it’s not that heavy.
Also, like you we use space heaters. The sealed “oil-filled radiator” type. I have like 7, but only 3 or 4 are in use at any given time. Only use for the furnace is a quick warmup in the morning, but we would forego that during a power outage. Also, the basement stays cooler and warmer than upstairs depending on the season.