Welcome to Hewitt Reserve! While it's not the prettiest park in Adelaide, it is a recreational hub for the local community, with cricket, netball and tennis the predominant sports enjoyed here. Exercise groups and dog owners also find their way here at all hours as it's a great spot to take in the fresh air and stretch one's legs...
To find the second location:

Near the listed coordinates, there are several pieces of information. I don't like people who are two-faced, but this is the sort of information you are after! When you've found the right info, all you have to do is pick out the letters listed here from the alphabet decoder above. (the counting does NOT include punctuation or spaces)
Line one: letter 1, letter 4, letter 5, letter 8
Line two: letter 1, letter 5, letter 9
Line three: letter 1, letter 6, letter 9
Line four: letter 1, letter 2, letter 14, letter 18, letter 25, letter 33
To find the third location:
At the second location you will be standing near a street corner. You'll need the name of one of these thoroughfares, and the type of the other (eg street, road, etc). Use the two grids below to match the name and type to the missing coordinates.
South 03_° _ _._ _ _', East 13_° _ _._ _ _'

To find the fourth location:
At the third location you will find a metal 'box' of sorts. No, not an Eclipse container, it's a different kind of box and a bit bigger. There is a brand name stamped onto this box. If you substitute the letters ABCDEFG for the letters in the name on the box, then you should be able to use the alphabetical decoder from puzzle 1 to solve the co-ordinates below
Ground Zero: South 035°01.BAC', East 13E° 37.DFG'
When you've found Ground Zero, hunt around for something that is out of place. Keep an eye out for muggles, and please replace the cache exactly as you find it :) Happy caching!