Laporte's Deal is pretty straight forward Play the 40 Million Euro Release clause.
Marquinhos I would like to Avoid due to PSG.
Stones I have no clue if he even wants to leave the UK
Gimenez would be my Choice IMO. not sure of Simeone is willing to let him go though.
I remember reading he was on around 9m before his renewal. I don't think that 12m figure is far off.
Laporte would cost too much due to the tax thing in Spain and his buyout.
You can forget about Marquinhos as Nasser won't sell.
Gimenez is good but isn't ball playing CB
Stones
Not really sure how it's calculated, but the news saying the limit is 70% and Barca exceeded by 3% leads me to believe it's a percentage based on total turnover (revenue). So basically 70% of income. They either need to increase revenue or decrease salary, or both. And yes, that would be gross salary.
Getting rid of useless players taking away chucks on available salary is a good step. Offloading Vermaelen and Mathieu who combined make about €8-9 net and getting one of Laporte or Gimenez would improve the team and save on salary too as the player is unlikely to alone make €8-9M.
Mustafi then? But his buyout is the same as Laporte's I think.
Paying a buyout clause also activates alot of extra taxes we have to pay, so we can add another 15-20m to that €50m with taxes.