Ndombele, Arthur, Rabiot then Lemar. But Ndom/Arthur are well in front of the other two.
Oblak, DDG, Alisson then MATS. Very, very tight and completely down to opinion.
Lenglet is worth keeping unless there are better options? Valverde seems to like him a lot, also Pique is 32 so likely to slightly less involved in 38 league games + Copa del Rey + Champs League - it's a lot.
I wouldn't be too fussed about getting Javi Martinez, but the duo is much the better deal.
If you're not too bothered about the ratings sell Godin, if you need the 94 then I'd sell Tah.
Both would be a good buy, Skov Olsen may reach a higher rating sooner because he'll be more likely to get game time at Bologna compared to Elmas at Napoli (obviously assuming both deals go through)