Correct. Not sure why I put 5%. It might be my age, or cos it was early in the day.Fa Cup allocation is 15%
FA have said pitch won't be made smaller.
As for tickets the PL rules are quite simple: The minimum allocation is 10% of stadium capacity or 3,000 whichever is lower.
For the League Cup it's 10% of capacity, and for the FA Cup and CL it's 5% of capacity.