We get spiders too, mostly in winter though, I guess they're looking for warm places. And we still heat with wood, so they must come in with the wood at times.
We've had a couple of snakes in the house...both babies. Both very unwanted!
but we caught them and let them loose. I don't kill anything like that, they shouldn't be in the house, but their not hurting anything either. They have a right to live...just somewhere else.