Both are good(great) players, no doubt, but as far as DM go, I'd prefer Gonalons, because I think he suits the team better (less offensive and more versatile) and probably would be cheaper. But don't get me wrong, Schneiderlin is top player.
Higuain - I haven't seen him much in Napoli, but if he isn't much better than he was at Real, I don't want him.
As far as CL go, I think it's more down to form and big game performances, so I don't wanna do these predictions, especially because we can struggle in big games and our form is up and down every few months.