Sorry to hear about the loss of your cat. We had a beautiful orange feral in the area and the poor thing met his fate the same way, seems like cats just don't understand how dangerous roads are.
Our two Bengals are kept indoors, they were both rescues and came with lots of baggage . The male, Makena, had been living outside and he hated being kept inside all the time. We struck a comprise and he walks and hikes with us on a leash daily (weather permitting.) Makena is very bold, adventurous and outgoing - I am not sure he would ever really be happy inside all the time. He has become so accustomed to his harness and being out with us, that he really does not want to go out on his own anymore. It turned out that walking him was not just for his benefit. Taking a few minutes every day to just enjoy being outside and walking with Makena has become one of my favorite things - probably lowers my blood pressure!
Our other cat, Lilia, was kept indoors in a small room. Just being allowed to roam free in our house was at first overwhelming for her (had to introduce her to it slowly.) Lilia is terrified of being outside and we can't even put a harness on her to go to the vet.
Like other shave said, I think making sure that cats have a stimulating home environment is key. We have lots of toys that we rotate for them, several scratchers, several windows with deep sills to sit in and bird feeders outside. Makena and Lilia play together a lot, seems like two cats do better than just one. We also do some interactive play or activity with them every day - they seem to appreciate even just a few minutes of having a toy tossed or chasing a string toy.
I did not always think this way. I was raised in farm country where keeping a cat indoors, or worse walking a cat, would have been laughed at. We had cats that lived outside and I bet none of them lived past 10 years. But living in an area with roads and fast traffic, seems best to keep them indoors. If we owned many acres in an area where their were no roads nearby and we needed rodent control in a barn, I might think differently.
Eric
Our two Bengals are kept indoors, they were both rescues and came with lots of baggage . The male, Makena, had been living outside and he hated being kept inside all the time. We struck a comprise and he walks and hikes with us on a leash daily (weather permitting.) Makena is very bold, adventurous and outgoing - I am not sure he would ever really be happy inside all the time. He has become so accustomed to his harness and being out with us, that he really does not want to go out on his own anymore. It turned out that walking him was not just for his benefit. Taking a few minutes every day to just enjoy being outside and walking with Makena has become one of my favorite things - probably lowers my blood pressure!
Our other cat, Lilia, was kept indoors in a small room. Just being allowed to roam free in our house was at first overwhelming for her (had to introduce her to it slowly.) Lilia is terrified of being outside and we can't even put a harness on her to go to the vet.
Like other shave said, I think making sure that cats have a stimulating home environment is key. We have lots of toys that we rotate for them, several scratchers, several windows with deep sills to sit in and bird feeders outside. Makena and Lilia play together a lot, seems like two cats do better than just one. We also do some interactive play or activity with them every day - they seem to appreciate even just a few minutes of having a toy tossed or chasing a string toy.
I did not always think this way. I was raised in farm country where keeping a cat indoors, or worse walking a cat, would have been laughed at. We had cats that lived outside and I bet none of them lived past 10 years. But living in an area with roads and fast traffic, seems best to keep them indoors. If we owned many acres in an area where their were no roads nearby and we needed rodent control in a barn, I might think differently.
Eric
If you don't want the brother to do the sister, just do it around 6 months and it's fine. The female will most likely not get her heat before 6 months (VERY rarely), and the male won't be ready yet either before that time. If you notice your female cat acting differently before 6 months make an appointment, or if your male starts to roar like a lion, jumps on the girl or starts peeing everywhere, get him helped ASAP (within that week). 
