1) You can get a 45 degree PME for $150US to $250US
2) Just get an Acute Matte screen to your preference. I have one with long crosshairs for lining up vertical lines. I did not like to one with the two microprisms.
3) Not so, with a hotshoe adapter only, I can use my Nikon SB800 on automatic mode. The 503CX which I have and the 503CW [and others] with the special strobes measure the light bouncing off the film. I have not found that degree of control is necessary.
4) Fly out and meet me when I am in Los Angeles and you can handle my Hasselblads [503CX and 903 SWC] while I crack open a bottle of Crown Royal.