I think he'll be a star in SL. He's a class above Roberts in terms of what he's done in the NRL. On his day he's the best running stand off in the NRL bar none. He's not a great organiser, can hog the ball and his defence can be targeted, but if he's on he will win matches on his own. Whilst I would have liked Leeds to have signed him, its great for SL to sign someone like Austin, who's one of the most recognisable NRL players there is. Given his daft goatee-hair combo he could and should be a PR dream as well.
I thought Roberts would go well for you, but Austin is genuinely a step above him at his best.
Re England, I think he's eligible but it was McNamara who was looking for England-qualified NRL players. McNamara did make a point of saying that he wouldn't chase anyone, it was up to them to make the move. Personally if he plays well for Wire I'd love it if he put his hand up for England, we're desperate for a second halfback.