I have been to the Aussie Open for the past few years so I will try and answer your questions as best as possible.
Ok, if memory serves me correctly, you can buy ground passes at the gate but I'm not 100% sure. If you go to any newsagency that has tickettek you can buy your tickets there even on the day you actually want to go.
i'm not sure what sections of the draw play first so I don't know when Kim will play. We'll just have to wait and see when the schedule of play is released. I think that is usually done on the Sunday but as I said, you can buy your tickets when you know exactly what day she is playing.
With the ground pass, you can go on any court except Rod Laver. (that's all outside courts and Vodafone Arena). Kim usually plays on Vodafone so you will have a good chance of seeing her. The only people you probably wouldn't get to see would be Lleyton, Agassi, Williams sisters and maybe Capriati because they always play on centre court. They do tend to put on quite a few of the top 10 on Vodafone so the public can see them. Only advice I have is if you want to see Kim there, get there early coz you don't have a guranteed seat and the place fills up pretty quick when she is playing
And the last question, as far as I know, Kim and Ai aren't playing doubles next year.
Hope this helps and if you have anymore questions just ask.