I quite like Weimann in that position. It's the number 10 position, although he plays more of a high energy role, rather than playmaking, and defensively will try to get at Barry and McCarthy who will sit deep (he did a good job on Gerrard against Liverpool). But he can hit either flank when we attack and also get beyond the front two.
I'm not sure we need to go 3 at the back. In principal, if Bertrand and Bacuna keep on the front foot, it should be alright, but that requires keeping the ball more effectively. In that respect I think Holt could do well. If you play it to his feet, the ball will stick to him.
Benteke will probably pull to the left quite a lot I'd imagine and maybe drop off too to link up play.