I found these old soccercards yesterday and i need help

Yesterday, I came across some old Dandy Gum football cards (1986 World Cup), and I’m completely new to collecting soccer cards. I wanted to ask:

• Which of them has the most vaIue?
• Should any of them be graded? (noticed that the Maradona card can go up to €500 when graded)
• What is the best platform to selI them on?
• Is it likely for their vaIue to rise in the future?
• Should i selI them

Thank you!