Nini

Hiya Guys! I'm new to this forum and will try to be as clear as possible. :) I'm about to buy new gear for videography pretty soon and have already chosen to go for the GH4, that i will use with these lenses : Voigtlander Nokton MF 35mm f/1.4 (77mm with crop factor), Nikkor 35mm DX (56mm with speedbooster), Nikkor 50mm FX (80mm with sb) and a Nikkor 18-55mm DX (28,8-88mm with sb). I applied a 2,2 crop factor for Voigtlander lenses and 1,6 for the Nikon ones (DX and FX). Is this correct? I keep seeing different crop factors all over the internet. The main use will be documentary and travel videography, so I'm trying to get good and sharp gear easy to travel with as I'll be shooting alone or with only one person. I've read several threads on the eoshd forum, reviews... and still have a few questions concerning ND filters. It seems like I should get a variable ND filter with a 77 or 82mm diameter. The max budget for the filters (one VND or filter system) would be 300/400 US dollars tops. - would you recommend a VND filter rather than a filter-system + ND filters for my use? - my Nokton diameter is 43mm, do you know if a step up ring 43-82 mm or 43-77mm exists? I couldn't find one over the internet. - if you faced this problem, did you find a solution? - would I get vignetting on corners with wide lenses even with the crop factor? - Reviews seem to highlight the Heliopan and Tiffen VND, are there massive pros for one rather than the other? I'm sorry for this long post! One question always seems to lead to another one... Thank you very much to those who will read and answer me :) And a huge thank you to all other posts and people in the forum for the previous topics that helped me. Woooo!