This is in fact a phobia of it, I'm not certain on the name but many people are afraid of the unknown. For example it could be something quite small on a large scale like what might happen next year or it could be a big thing like knowing or not if you'll move out or if you and your partner are pregnant to the unknown of what me be of the birth .. Many things are unknown and it is only natural to feel afraid of them. Personally I am afraid of death to some extents and I'm afraid for if I have kids if they might carry my genes for anger issues, asthma, learning diffiulties and even hyperactivity issues.
of course they do. There are many example today and through out history that proves people are afraid of things they cant understand so they try to get rid of whatever it is or avoid it. I know many people are afraid of aliens because they are unknown and dont understand them. People are afraid of homosexuals because they have a misunderstanding of them. So yes
Not necessarily everything. I don't understand many things, it doesn't mean I'm afraid of them. It just means I don't understand. If I don't TRY to understand, perhaps then I'm somewhat afraid. It just depends on what it is.
Not everytihng, just some things.