All articles say the same (16m€/5y).
I don't know if he's ready for the premier league yet. He still has a lot to learn, hopefully he'll get some time to adjust (probably not ).
I wouldn't have paid 16m€, that's the highest amount in the history of Belgian football (I think). I don't think he's worth it yet, he might be in a couple of years though if he keeps improving the way he has been the last couple of years.