1. Like dogs, do goats need to be exercised?
2. What is the minimum requirement of area for a goat so that is does not require exercise and is happiest?
3. I sometimes plan to have two groups of goats. One with a male and one without one? I'll keep one group for breeding and the other for milk production (Like when you said that goats for milk should be kept separately from bucks). Is it a good idea?
4. Is there a specific mating season for goats?
5. What causes bucks to become aggressive?
Goats need exercise, but usually get it themselves. If they are in a limited space, each goat is said to need 20 square feet of area outside their living space. They are happiest being able to forage on a variety of woody plants and shrubs.
I recommend and I keep goats in two separate areas. One is females, pregnant, milking, and kids. The other is bucks and male goats that have been castrated and are more than about 5 months old. You have to be careful that bucks do not injure smaller males. I "hand breed" my goats, meaning that I bring the buck and doe together so I know when each one is bred. This way I know when they will have their babies so I can be there in case anything goes wrong.
Most goats go into estrus when the days start to become shorter and come out of it in late winter. Some breed year round. The bucks' odor can cause the does to go into estrus and be able to breed.
Bucks get more aggressive during breeding season. Some just seem to turn mean. Others were played with by pushing on the head when they were younger. They then learn that it is okay to head butt people. If a buck starts to get aggressive, you can use a spray bottle with water to spray them. That often stops them. But it is important not to play rough when they are little, not let them jump up on you or head butt you. Never push on the head.
I hope this answers all your questions. Let me know if you need more information.