I think you make some great points & I agree with a lot of your ideas. I do, though, think that Luiz will be partnered with Kamara or Dendoncker and then Buendia will play a more advanced midfield position. I'm also interested to see what we do in midfield with Tim and Aaron returning from (what looks like good atm) loans in the Championship. Then add in Sanson, McGinn, Nakamba, Chambers (not sure he would but can play in the midfield). That's 9 players for 2 or 3 spots. I don't think Nakamba has a future here, and McGinn just isn't PL standard. That still gives a lot of depth (maybe not high quality) but I think we need to get a couple more out/loaned.
Lo Celso just makes so much sense, considering his history with Unai.