Yes, they can get all kinds of nasty things from being outside.
Its not really like cats like the dark. Cats are animals that hunt in the night, so they will prefer being outside while dark.
Indoor cats usually live longer than outdoor cats because outside cats are able to get more diseases, rabies, or hurt/killed by another animal. Indoor cats are less likely to get diseases or get rabies, which is why it is incredibly important to vaccinate your cat when required, especially when it is allowed to be outside. Outdoor cats are also at risk of being hit by cars. A cat cannot outrun a car, and such incidents are very common.
Calicos can live inside or outside. It depends if they were born inside or outside.
There are no specific breeds of cat that are typically "outdoor" cats - it really depends on each individual cat's personality. Some cats prefer to stay indoors all their lives, while others like to go outside when they want to. Being outside allows independence and freedom. But, being an outdoor cat can be dangerous if you live in a urban area. Any cat can be an outdoor cat (if it so wishes - never try and "force" a cat to go outside if it doesn't want to) as long as it's not declawed. Also, most pedigree breeds are kept as indoor cats, due to their value. Some pedigree breeds are known to be ignorant about roads, and are at risk from being stolen.
cats mostly live in a barn or a house and outside
Cats do sometimes go outside to die,its because they like to be alone to do so, so going outside is a way they can find somewhere to be alone.
No they shouldn't be left outside all the time. You can leave them out for about 12 hours, but they still need love.
I found a lot of nice furniture for cats that I loved as I have 2 cats myself, my favorite came from DIY show off where they have an outdoor walk for cats which is a basically a walkway where cats can go outside and get fresh air without being in danger from traffic or other wild animals that are lurking about.
Domestic and feral cats are at times eaten by hawks, coyotes, raccoons, owls, foxes and dogs. Cats that live outside homes are at greater risk of being preyed upon.
Many domesticated cats, especially those that rarely venture outside, use litter boxes that are inside the house.
Cats are originally desert cats, so it won't be too bad for them, but it isn't good for any mammal to be outside in extreme heat. Make sure your cat has plenty of water.
Sometimes people let their cats be outside cats because they do not like them in the house. Other times they do it because they think it cruel to confine them. Outside cats have been known to have shorter life-spans than inside cats. They are exposed to more things.