Tango Tango:
There will be approximately 40 candidates for the first interview. For the second interview, there will only be 10 of you for each session.
Jessie Blue:
Yes, clearing solo is the first important hurdle you have to clear during the Jandakot phase. If you are not safe to fly alone, how will you be able to fly passsengers (or cargo) next time? Some people can do it, some people can't. That's the sad truth. And you won't know until you've tried.
As for positioning, it depends on which allowance you're talking about. I don't have the exact details, and I don't think it should be discussed here anyway. As for the lonely part... well, it depends... if you're flying passenger, then there's cabin crew to go out with (if you wanna join them)...
As for diving, yes, you will be able to find time to pursue your other interests when you are in Jandakot.
Predator:
There are interviews held on a regular basis; but everyday, there are applications coming in, so you may have to wait for a while before you're called up for interview. My suggestion is to send in the application anyway, and see how it goes from there. I think it would be better for you to make a decision when you're offered the position (after clearing the interviews AND medical).