PS4Gta 5 question

Hello MPGH, I have some questions mind answering them?
1. When i buy gta 5 for ps4 (USED) do i get the old person saved files or not? - FOR EX. THE PERSON IS LEVEL 100 DO I GET TO 100 OR DO I START OVER?????

If you come over PS3, the system will see that you already have an account and you will use it.
Or if you already have a savefile on the PS4 all will go normal with that save.