You will not know for sure until you try it.
But you will probably get some chicks that grow well, and some that do not grow as fast or as big. I can't say how many of each type you will get.
Yes, that will probably work fairly well.
Either way would probably work fine.
When weighing, consider the males and females separately.
It might be best to keep 50% of the females, but only the best 2 or 3 males (or for a large flock, keep one male for every 5-10 hens.) The very minimum...