Noob needs help with step ring configuration!

[Germy1979]

;D oh.....hi!

So i picked up a Kowa Prominar 16H (American version) for a steal on Ebay.  I Also got a killer deal on a Zeiss Distagon 35mm f/2.  I'd like to use both on a GH2.  I was getting a Fader HD Vari-ND filter 58mm for the front of the Zeiss...  But i found the deal on the Prominar.  In Andrews book it says the Kowa won't vignette with a 35mm on the GH2.  From what I read, the Kowa's back end has a 50mm thread?  So my question(s) here are:

1.  What step ring do i need to attach the two lenses?  58mm to 50mm step DOWN ring, or a step UP ring?  or a clamp setup?  Would it vignette stepping down to the Kowa?

2.  Can i use the ND filter in there anywhere with an Anamorphic lens on the front of the Zeiss?  Am i supposed to place it in between the two with some kind of step configuration?  How do you guys do this? Should i get an ND filter for the front of the Kowa instead?

I'm sorry if these are dumb questions... Lol.  I've tried looking this up with vague answers.

Thanks in advance guys, any help would be great!  I don't want to use duct tape, lol.