Specific phobias can happen at any age
Since they are fictional characters I don't think the fear of unicorns is much of a problem.
Nobody is really certain - if we knew for sure, we could always cure them! It's thought that some phobias start with childhood experiences that are not processed in a healthy manner, but allowed to grow out of proportion. However, there are many phobias that we just don't know about. Sometimes people develop phobias that they cannot explain.
Generally phobias occur when the sufferer has had a bad experience with the object of their phobia. Common phobias that stem from these types of experiences are spiders, dogs, and the fear of being ridiculed. It is also possible that we biologically inherit some phobias from our parents. Others develop phobias later in life and are never able to determine the cause. The important things to remember are 1) you are not alone, and 2) there are successful treatments for the condition.
The phobia of phobias is Phobophobia.
Phobias are an aspect of psychology, which is considered a science. So yes, phobias are a science of sorts
Freud said phobias were repressed conflicts, were as Watson said that phobias were learned
The independent variable would be either gender or age (should choose one or hold 2 experiments) the dependent variable is the phobia the control would be the things similar between every person questioned
Honestly, you can have a phobia of anything! There is even a fear of phobias!
phobias are just natural things we have and noone can stop that
Generally speaking, yes, phobias can lead to compulsive disorder. Still, it depends on the severeness of the phobias.
You can develop bi-polar disorder at any age.