Queries about Employment in Spain

I am currently trying to complete some research on Spain and was wondering if anyone could answer the following questions:

Are there apprenticeships in Spain? If so, is there age restrictions on them?
Are there different minimum wages dependent on age?
How often do minimum wages changes?

Alternatively, are the any specific websites that would direct me to the answers to these questions?

Many thanks

question 1a/b
answer in Spanish.
question 2
Answer in Spanish
question 3 when the government calculates it is needed.  :/  I have read it is going to be guaranteed to rise over the next 3 years
Google is your friendly website to find out more.