Should one put the ps4 now across or lie down?
Does not matter! As you like and it fits!
I'll put it down because it's just too heavy and falls down. But if you order such a part where the playsi can stand, then you can stand.
Ask it because the fans are on the sides
One should believe the console horizontally put / put.
If one intended to use games as a disc version, the vertical position would be detrimental to the drive. I've read that at least once or learned on YouTube.
PS: Maybe the internal hard drive would be damaged by the vertical position, because it is basically just a big disc.