Is it possible that I download Star Wars Battlefront 2 on the PC if I already bought it on the ps4
You can log in to your EA account and see if you can then download it to your PC, otherwise you will have to buy it again
No, these are two completely different platforms that have nothing to do with each other.
Unfortunately you would have to buy it new
No, but you can buy it again.
To the best of my knowledge I don't think you have to buy it new.
You have to call EA's support hotline. Explaining you how to do it.