MySQL DB query

I have quite a complex page I need to write a number of queries for in order to display chart data from a database. MySQL.

To try and explain at a basic level:

My data is stored and grouped on a project by project basis and sub categories within that project. I need to pull all data that is the same, same question_text in different projects.

I need to display as an overall chart all the data that exists about a single question within all projects. (however projects will be filtered by client).

The data is collected on store visits, and several visits can be made to one store, I only want to use the data from the last visit to any one store.

The data will be displayed in a chart (already set up and working, i just need to filter the data as above).

Hopefully that will explain what I need but I can obviously give more detail as required. Hopefully its just a quick job for you wizz's out there.