Try to clear up data model 'questions' and 'information'

An attempt to make our use of 'information' (metadata and data)
consistent in the file. Additionally, try to clean up para 3 in
section 2.1.2 which defines important questions data models may
answer.
Rewrite of section 2.1.2.

Provide definition of namespace, clear up and provide examples of
namespaces, make use of figure 1 for examples.