Regarding recognizing which snake is which - I'm not an expert but based on my life experience here's some info:
Copperheads' heads and other poisonous snakes native to the US are shaped like the old fashioned pine box coffins you see in old movies - it's why we call them coffin-heads here in the south where I live. It's that wide jaw that narrows in a squared fashion toward the mouth that makes the shape like the head and shoulders end of the old fashioned coffins. The non-poisonous snakes have a more oval shaped head. Also, poisonous snakes have more slit-like eye shape (like a narrow oval) and non-poisonous are round-eyed. Also, if a copperhead is nearby, you often can smell them. They smell like cucumbers, but weird cucumbers. If you ever smell it and know it's a copperhead, you'll know what I mean.
It's my understanding (but I'm not a herpetologist) that poisonous and non-poisonous snakes can't cross breed; one has live babies and one lays eggs. Again, I'm not an expert, but if this is true and you learn to recognize the head and eye shape, you should know when to detach the snake's head, if you choose to let the non-poisonous ones live. And be careful, just because its head is detached doesn't mean it can't still bite. It can't strike any distance if it's body isn't attached but if you touch or get too close to it, the head can still bite until the nerves are completely dead.
But my philosophy is "see snake, kill snake" and "the only good snake is one that's been separated from its head and disposed of". I'm not going out to hunt them down, but if they move into my territory, they are fair game. I'm don't want to routinely walk across one that I've let stay in the neighborhood and have to analyze its head every time I see it to determine if it's poisonous or not. And if you catch it near your hen house or other food source they like, it's probably been there a while and/or is planning to stay as long as the food supply is there. If they have shelter and food, why would they move on? And catch and release elsewhere (unless you drive very, very, very far, they'll just come back. And then, seems to me, you are just dumping your problem onto someone else.
And by the way, in my head-separating experience, a rounded end shovel works best and gives you the most strength in striking. A flat edged shovel will work in a pinch but takes more muscle because that flat end just doesn't cut like that rounded edged shovel. Another good choice is a sturdy floor scraper - it's like a hoe but sturdier and the blade doesn't bend 90 degrees at the end but is straight in line with the handle and gives you good striking power. A hoe by design puts your arm strength at a disadvantage, having to reach out far from your body and strike down with little muscle power behind it. A shovel (my favorite) can be held to reach out quite far with your arms still pretty close to your body and your muscle power is a downward-angle strike that you can put some weight behind. I have a relative that prefers a hoe, and sometimes her strikes on a snake's neck just bounce off and she has to keep trying. They are pure muscle under that scaly skin. I don't want to have to hit it repeatedly while it's trying to strike or run, so a hoe for me is a last resort.
There are snake repellents out there but I've read extensively about them and found that some just irritate the snakes and not in the way that makes them flee. So I'd have to be positive I had the repellent that actually repels the snakes. Otherwise, you're just setting yourself up to encounter a mad copperhead instead of one that's sated on eggs or whatever else it's in the area to consume. Dr. T's is supposed to be the best (
http://www.havahart.com/snake-a-way-repellent-granular) but I'VE NEVER USED IT PERSONALLY. I read somewhere they have the military contract for use overseas where our troops live in tents in snake infested areas and it's supposed to be 99% effective. It's a combo of ingredients that cause the snake's sense of smell to be jolted to the point that it's automatic reaction is to flee. But flee how far? If it's 200 feet, it's still on my property and I can't cover acres of ground with an expensive repellent. But if a small area is all you need, that might be the answer for you. Also read the reviews for it on
Amazon, they're about 60+% favorable.
In my research, the repellents that aren't Dr. T's specific combo of ingredients (but only 1 ingredient or different ingredients) you get the irritated snake instead of the fleeing snake. So I can't recommend any certain one but it's an avenue you can pursue and make your own decision.
Hope this info helps.