few questions back atcha.

1. What strain are you growing? That will greatly impact the amounts of nutes you use. It also really helps to know the brand of nutes since each brand has it's own directions to follow.

2. Got your ph meter right?

3. How far away your light is depends on too many factors to just tell you a number; unless it's like something say......three feet from your plants. New clones and seedlings need to be introduced to a 600w slowly......otherwise it can fry them. Once they are used to the lighting you can begin to lower it.

4 Can't help you at all about seed companies......don't live in Australia.

good luck.