A: Limited only by your file system. exFAT/NTFS can handle >200 GB easily.
Several tools exist depending on whether you prefer working on a PC or directly on your console. pkg merge ps4 tool
As the scene evolved, newer installation methods like Remote Package Installer allowed users to send files directly from a PC to a PS4 over a network, bypassing the need for external drives entirely. A: Limited only by your file system