Panasonic GH2 video setup Q's

Looking to upgrade from my Nikon D3100 with something more geared towards video and I've decided on the Panasonic GH2 with the Driftwood hack.

I have a few questions and I'd like comments on the gear I've picked out to go with it.

Lumix 20mm f/1.7 Aspheric G- Series Lens ~ I'll be shooting low-light street and people portrait, is this the best lens? I could/would stretch to the Voigtlander f/0.95 25mm but people say it doesn't start to get sharp until f/1.4, but are we talking about 20mm f/1.7 sharp or in another league altogether?

I'll be recording on 176Mbit and need a fast SD card, is something like this Class 16 card going to be fast enough or do I need a 633x Delkin? ~ There is a huge price difference!

Pretec 64GB -
http://www.newegg.com/Product/Product.aspx?Item=9SIA0KV05A0424
Delkin Devices 16GB Elite -

http://www.bhphotovideo.com/c/product/804734-REG/Delkin_Devices_DDSDELITE633_64GB_64GB_Elite_SDHC_633.html

What sort of adapter do I need to use my existing Nikon lenses, is there any benefit to the expensive ones?

Can I use a magnified viewfinder like one of these with the GH2? -

http://www.amazon.com/gp/product/B004HD3G6Q/ref=ox_sc_act_title_2?ie=UTF8&m=AL7LHK6Q9LVTS

I'll also need a tripod, I've never had one solely for video so I'm not sure what to look for... here are a few I've picked out:

http://www.bhphotovideo.com/c/product/755484-REG/Manfrotto_MK394_H_Photo_Movie_Kit_Aluminum_Tripod.html

http://www.bhphotovideo.com/c/product/687334-REG/Oben_AC_1400_BA_00_AC_1400_4_Section_Aluminum_Tripod.html

http://www.bhphotovideo.com/c/product/349250-REG/Davis_Sanford_PROVISTAIR18_ProVista_Airlift_Tripod_with.html

Lots of questions but I would appreciate any opinions and advice you may have.

• Dan