I'd seriously look into doing it yourself, if your x is confident enough to be able to argue for himself. Otherwise it can get really really really expensive (my firm is making $355 per hour for my time!) YOu cal always get free advice from Legal Aid, especially in regard to drafting documents etc.

It will always depend on the particular child. An immature 8 year old's wishes won't carry much weight. Neither will how the parties broke up. The Court does not really care about fault, it's all about who is the best parent for this particular child at this particular time.

The problem that your ex faces, is the recent changes to the Family Law Act. "Shared Parenting Responsibility" means that the first thing the Court must consider (most of the time) is equal time for each parent with the child.

I'd see the Sunshine branch of Legal Aid, just to get an idea of how it might all work out.

Best wishes.