There is lots of info on here about touching in red seats.
Search for 'woolite' that will return all the info you should need about cleaning them.
As far as re-colouring goes, you can get small touchup sticks from ebay. Search something like "bmw coral red" (replace coral red with the actual colour of your seats) and it will show you some touch up sticks for £9.99
Very easy to apply and buff. Make sure you don’t sit in them for 24 hours, especially if you wear white.
Very few leather car seats need nourishing, as they are covered in plastic. They just need a good brush and a clean.
Higher end cars or some options on the Z have "proper" leather but uncommon.