Yes, but diagnosis is much more difficult the younger the person is. It can easily be confused with many other things.
Kids can definitely get Bipolar, especially if one (or both) of the parents are Bipolar.
No.
No.
Bipolar does run in families, though it doesn't affect everyone.
Its over 9000.
Bipolar is often inherited. A common trigger is a relationship which creates insecurity.
No
unknown
can it? yes, dramatically.
It doesn't. Get lost!
no known effect
Yes. Juvenile Rheumatoid Arthritis (JRA) can appear in kids that young.