Depending where you go. If you go to the coast there's a lot of humidity. On the center the climate is very dry and the nights are not so hot. Typical day in interior spain temperature can go from 10C to 35C easily.
Still pretty hotter than the rest of europe overall.
Climate wise the worst is that we are very vulnerable to climate change. Our highest temperatures are already pretty high so higher temperatures in summer will be deathly. Also some parts of Spain are vulnerable to drastic climate events, recently two hundred people die in a heavy flood in Valencia.
Depends on the animal. Home raised chicken, for instance, can almost live on human lefts.
Insects also eat things that humans really do not consume, for instance.