Thank you for such a detailed response! The endosperm being the “food” for the baby plant germ is actually a really helpful explanation as i usually just skim across the technical terms because i confuse myself easily 
If i could just grow one single crop for corn and pick it early for sweet corn then let it mature for grain, that would be so beneficial and easy! Flint, dent, flour, popcorn, sweet, everyone seems to use the terminology slightly different. I notice some are super stumpy and wide at the sides, others a bit longer with the dent. Popcorn i think is easy to identify with the perfectly round shiny appearance…?
Id love to search for some of the sweet corn varieties that you recommended! For now i will just be planting the Canadian GTS sweet corn, along with a few old packets ive been hanging onto for years that i never attempted to grow until this season. Im very excited to grow corn.. i love it so much, both sweet and grain. It seems like an excellent staple crop for grain supply with limited space available! Next year i will see if i can find some Blue Jade, Hooker Indian Sweet or Aunt Mary.
Much appreciated for your hints at when to plant the corn. I have the grain corn seeds soaking right now and will plant em tomorrow. Though, im a little worried that i chose not to attempt identifying/dividing the seeds a bit… hopefully pollination wont be too atrocious 
^Here’s a pic of what i mean with the different shapes. The red i think is either Painted Mountain or Bloody Butcher and the pale one is from the gts grain mix