Each chicken has its own unique personality. You can't really tell exactly what one individual chicken will do, but they do have tendencies in some things. Sometimes we can tell what they will probably do.
1) Do roos practice mating prior to being fertile?
Possibly. Mounting is a form of dominance. I've seen mature hens mount immature pullets to show dominance in an all-female flock. But the odds are that he is not just practicing if the hens allow him to mount them or even if he forces them. If you want to know if your eggs are fertile, you can look through this thread. It has pictures to show you the bull's eye you are looking for.
Fertile Egg Photos
https://www.backyardchickens.com/forum/viewtopic.php?id=16008&p=6
2) Do roos come fertile before they grow spurs?
Yes.
3) Am I going to have an issue this winter with the two roos fighting?
That is one of those that is hard to answer definitely. With hens present, two roosters will determine which one is the boss. Sometimes you don't even notice this happening. If one is sufficiently more dominant than the other, it is more intimidation than fighting. They flare their neck feathers, jump at one another, and it immediately turns to one running away and the other chasing for a short while. Sometimes they fight to the death. Which they do depends on their personality much more than size. With your two, they already know which one is boss, but they are not totally mature. As they continue to mature, there may be other flare-ups as one challenges the other. Again, these could be more running than fighting or they could be real serious. You just never know. But when they mature enough to dominate the hens and assume their flock master roles, they can and usually do form a good team working together to protect the girls.
4) Right now, one of them likes to eat raisins out of my hand, and the other doesn't trust me. Should I expect this to continue?
No idea. I don't hand feed mine.
5) They have 8 hens to share. Will that be enough?
That's one that can't be answered. You'll see a magic ratio of 10 hens for each rooster that is supposed to be required, but it really is not. That 10 to 1 is the ratio commercial operations that supply hatching eggs use to assure a good fertility rate when they use the pen breeding method. That's where they may have 20 roosters in a pen with 200 hens. That ratio is really not valid for anything else, although it does make for a nice flock.
There are a couple of things you need to watch for, and they are worse with adolescent roosters with their hormones running out of control. Usually when the roosters mature these problems go away, but not always. Breeders regularly keep one rooster with one or two hens in a breeding pen without these problems showing up, which to me debunks the 10 to 1 myth. Sometimes people have reported these problems with one rooster and over twenty hens.
One is that the hens become barebacked. It is not unusual for a hen to occasionally lose a feather or two during a mating. That's no big deal. But sometimes a rooster will strip so many feathers off with his claws and spurs that he can cut the hen during mating. Chickens can become cannibalistic if they see another chicken bleeding and that chicken can quickly wind up dead. If you see this happening, there are steps you can take. You can get saddles for the hens that need them or you can clip the sharp points of the claws and spurs, making them blunt. I think the claws do more damage than the spurs.
The other is a bit more subtle. Sometimes the hens get stressed out by too much mating and will start to avoid the roosters. This can affect egg laying if it is real bad. Usually, once they both mature, some hens like hanging out with the rooster and some don't. If you see things like the hens staying on the roosts instead of getting on the ground so the rooster cannot have his way with them, you might have a problem.
I've had more problems with barebacked hens when I had my "best" rooster to hen ratios and absolutely no problems with ratios that some people say are real problems. Each chicken and each flock are different. My regular advice is to keep as few roosters as you can, no matter how many hens you have, and still meet your goals. The more roosters you have, the more likely you are to have problems, but problems are not guaranteed.
6) Do I need to make a bachelor pad? Right now, they they can climb up with the hens into the coop, but they won't come out the bottom ramp in the morning. They are too tall, I think. They are in a coop/run, inside another run, and the dogs keep the racoons away. I have to open the side of the coop to let the guys out. I let them all free range, when I can listen for trouble.
I would not separate them. They have probably sorted things out based on their maturity level. It is not unusual for mature hens to bully immature roosters, but as the roosters mature, that will change. If you separate either one or two of the roosters from the hens then put them together with the hens later, they will be back to square one on which one is boss. That situation often leads to a serious fight. Once they are together with the hens and have it sorted, I'd not mess with that situation.
However, you have a few options if you see problems. You can give one of the roosters away. I think that keeps your promise not to eat them. You can separate one rooster and never let him in with the other rooster and hens. You can even rotate one rooster with the hens for a while and then the other. You can build a separate coop and pen and keep each rooster with his own hens, never allowing them to free range together.
I can't give you definitive answers on a lot of these things. You might have problems and you might not. I do think the more room you can give them and the more you can free range them, the fewer problems you are likely to have. You do need to watch, especially for the barebacked hen problem, but that can occur in any flock and with any aged roosters. Good luck!!!
