Hey mate, welcome to the site. Theres a few stores on here you can buy them from.
I'm one of them and based in Adelaide. A couple from W.A and believe a couple from Vic and NSW too.
Who to collect is purely up to you, your fav player or someone you would like to collect. Could be a rookie or even a team.
New past and present look not too bad. Good value for the price.
Most boxes these days are 1 to 6 pack boxes and you are better off buying a box to be honest. All depends on budget and what you want to spend. Check out YouTube vids and on here to see what boxes or cards you like.
Hope that helps. Good luck and if you want any advice feel free to ask.
Brett