Quick home electric question

You may be able to run what you have listed... The fridge will have a high startup draw whenever the compressor kicks on but that will be a surge for a fraction of a second. The furnace blower may take as much as 1-1.5kW (1-1.5 kVA). So that ought to be OK with a 7 KW gen (which will probably be good for 4-5KW long term for most of the foreign made cheap gens).

With the 200A breaker only cutting off power to the disconnected meter base, that says the 200A panel is probably being fed from the 100A main breaker, in addition to that 100A breaker feeding it's own panel. That seems odd. OK... I see you posted that the 200A panel is being fed through that 30A breaker. NO WAY is that to code... But at least the 30A feed breaker looks small enough to trip before that feed wire between panels get too much current.

Someone used that 200A panel as a sub-panel in the rewire, and it is not safe to use the 200A breaker for the small feed wire size used between panels. So they jury-rigged it in via that 30A breaker. But it is like connecting the generator without a transfer switch..... it is not standard and folks forget and send power to the wrong places when the set breakers expecting the behavior to be normal.

It would be OK for general safety as you do have a whole house disconnect and current protection at the 100 A breaker. But who knows how heavily that 100A breaker is being loaded. And the 200A breaker back feeding to that unpopulated meter base is just another electrocution issue.... totally abnormal.

Can o' worms is right! Glad you are sorting this out and asked.