Flash advice needed for Hasselblad 203 FE

I've read informative posts regarding flash photography and Hasselblad. I have a 203 FE with PM45 (flash shoe in top). My lens is 80mm FE (no shutter in lens, this 'blad has a focal plane shutter). I'm new to MF, Hasselblad, have not even loaded the camera with film, but I have some. I'm looking at the Metz 45, I see various version online. I also want to use the TTL sensor, and I will need the 2 sync cables (PC and multi-pin, both on body, no PC on lens)? I assume that makes the flash go boom. Does the Metz have all I need or do I need a Hasselblad or Metz accessory?

If I want to use and old Vivitar or new Nikon flash with the PM45 shoe, do I need a "commander" with 2 cables between the flash and shoe to connect to the body (PC and multi cable)?

I read the manual. It focuses on Hasselblad equipment.

The Metz 45 unit you'll want is the 45 CL-4 (or CT-4).
It will do TTL-OTF control, but you will need the Hasselblad SCA 390 adapter as well.
The SCA 390 has a fixed cable with multi-pin plug, running to the contact on the camera body's side, and a detachable PC-synch cable, running to the PC-flash synch socket on the body.
You do not need to use that last synch cable with the 203 when using the focal plane shutter. You will when using the shutter in a C/CF/CFi/CFE lens.
To connect the Metz unit to the SCA 390, you will also need a Metz 300A cable.

I do not know if the other units you mention will work at all in TTL mode in combination with your 203.