Learning to play the violin also known as the fiddle
My oldest daughter plays the violin.  It takes a lot of practice
My violin has a hollow wooden body
I'm not sure about how hers is.  It was issued to her by her school.  It still sounds lovely though!
Smaller violin type instruments are called the piccolo
Isn't there also another smaller type called the viola?
Yes and another called the kit violin
Kit violin sounds like something that you have to assemble by yourself.  That might actually be something fun to try out.
Most violins have four strings
Just like a bass guitar, although I'm not sure for the same reasons.  I really am more of a brass instrument person.