Not optimal conditions! But I expect a lot will still germinate and longevity will vary depending on what the plant is. I'd try a few of each just to see if they will germinate before committing time and effort to sowing them all.

Some seeds stay viable longer than other seeds. If you have enough seeds, you can test them by soaking them in water for a few hours then wrapping then in a damp paper towel. Count the number that germinate after the usual germination time divided by the number of seeds and you will have a current germination rate.

You tell germination by seeing a small root develop. And by the way, you can plant those. I routinely do that with direct-seeded plants like corn and beans.