And that's a valid concern. Only my chicks get medicated feeds, but it's a good thing to worry about.
Yeah, the number of feed labels I've had to look through to find the right mixes for my rats - pig pellets it's pretty easy to get without added medications. Dog food and rodent food, same again. But I like giving females with young a bowl of layer's mash on occasion, and that tends to be where one finds all the "wonderful" drugs.
No they don't. At least, humans and dogs don't. For instance, there are whole colonies/communes of humans that are raised vegan/vegetarian from birth (for one example look up "The Farm", in Summertown right here in TN), and grow up to be perfectly healthy adult human beings.
I don't think there's been enough time or inclination to show how an exclusive (carnivore OR herbivore) diet affects an omnivore throughout its whole life. Vegetarian diets for dogs haven't been around long enough to establish whether a vegetarian dog lives as long as a raw-fed dog lives as long as a kibble-fed dog, for example. And I'm pretty sure the western concept of vegetarianism/veganism hasn't been studied enough to establish whether vegetarians routinely outlive and are more healthy in middle to old age than omnivorous or carnivorous humans.
Must admit that the vegans/vegetarians I've known have generally been either healthy but ALL OVER health conscious (i.e. they may have been healthy because they were very careful to make sure they got the right balances in their diet, did a lot of exercise, and so on) OR they were less actively conscious of their health, and were less overall healthy (more colds, worse skin, etc) than an omnivorous person with the same sort of activity/exercise levels.
I think, if you're designed to eat both types of food, there are probably things in that food that you need. Of course, the real funny is trying to get an Atkins/Paleo person and a vegetarian/vegan to see eye to eye on something...
As for the cannibalism question, I'm absolutely with ya.
But there it is
You sound like someone from Louisiana, their perspective and nutrition is...eclectic, sometimes
Nah, born in Albuquerque, New Mexico

Darn it, since moving to the UK my regionality is everywhere! Hear me and people say Canada (even people FROM Canada!!!) and now I eat like someone from Lake Charles*...
I've toyed with the idea of trying one of my homebred rats (it'd certainly solve the problem of "this male has gotten too big for anything I own" if *I* was eating them) but I can't quite get past the "Here he is, he's alive, now he's dead but he's still got his jacket on and LOOKS alive even if he isn't..."
* Only place in Louisiana we stopped, I have a good friend there. I don't remember him being particularly pragmatic about his diet!