Parliamentary Base Salaries: Senators and Members (Australia)

This is based on 2016 figures.  Below is an excerpt from the pdf.

Increases in the parliamentary base salary compared with average wages from 1968 During the 1980s the MPs’ base salary failed to keep up with inflation resulting in a decline in value in real terms. This was in contrast to the average which kept ahead of inflation and grew, in real terms, at an annual average rate of 0.3 per cent. As a result the base salary, which had been three times the average wage in 1975, was only twice the average wage in 1991. During the 1990s MPs were given increases to their base salary which allowed some catch up with average wages. However, despite this by 2011 the base salary was still only 2.2 times the average wage. In March 2012 MPs received an increase to their base salary of 31.3 per cent. This resulted in a significant increase in the value of the salary relative to average wages. At 2.8 times the average annual wage it is at its highest level in 37 years. The freeze on MPs’ pay for a year (beginning 1 July 2014) reduces the gap with average weekly earnings. There was no increase in MPs’ base salary in 2015.

Table 1: Base salary compared with average wages 1968–2016

http://parlinfo.aph.gov.au/parlInfo/download/library/prspub/4618589/upload_binary/4618589.pdf;fileType=application/pdf

What I’d be interested in knowing is why it is indexed to CPI?  Why not just gross salaries, then a column for tax and net salaries.  That is clearer.

My Question Time questions – In the Public Interest:

Why ratio allowance to average wages? What does this mean?  I have no idea what the ratio is? 
Why average wages when that skews towards higher wages given it is an average? 
Are wages inclusive of salaries? 
Why not median salaries (no percentages) just compare apples with apples?
Why not list all Senators and Members (names) and then sum data so it is clear what this means adn who is being calculated? 
Why not actual gross base salaries. 
Does this include Ministers?
What is the median travel allowance?
What are the median expenses? (over and above salaries)

Is there anything else the public needs to know of its representatives?