As you've already noticed, if you ask one question, you'll get 5 different answers, and 3 of those responders will claim that their answer is the only right answer. Thankfully, there are as many different styles of animal husbandry as there are varieties of chickens. Mama hen takes her babies out into the yard when they are several days old. They eat: soil, worms, chicken poop, chick feed, any insect they can get hold of. Coccidiosis is rare in broody raised chicks. So is pasty butt. Never heard of a broody raised chick having an impacted crop from eating grass in the yard.
Now, if chicks are kept in a sterile brooder, and never allowed to be exposed to the soil... they don't get the chance to develop their immunity. And if gobs of long grass are dumped in the brooder, they just might get an impacted crop. Long strands of cut grass are much different than grass that they can nip off from a chunk of sod. And that sod will have grit in it.
As far as medicated feed, it boils down to personal choice. I would never tell someone to NOT use medicated feed. Which leads me to wonder why some consider that they have to tell everyone they talk to that they MUST use medicated feed. Personal choice! I suggest that you do some of your own research, and come to the decision that makes the most sense to you. If Amprolium blocks Thiamine uptake in the cocci, I'm left wondering if it also blocks thiamine uptake in the chick. Regardless of what the answer to that question is, I choose not to use it. Never had issue with coccidiosis.
There's such a thing as too clean. I'd suggest that you take a break from the bleach. Studies have been done that show that chicks raised on bedding that has housed previous batches of chicks (dirty litter) benefit and actually grow faster, and use their food more efficiently b/c their guts are more quickly populated with good bacteria and fungi. When I raise chicks, I just toss a layer of shavings over the previous layer when ever needed. The soil from the sod just mixes in with the shavings. Put in sod when ever you feel the desire to do so!
Definitely. IMO, the biggest mistakes folks make is using a breeder that is too small, and giving the chicks too much heat.