What lenses for my Panasonic GH2?

What combination of the lenses below would make a good beginners package. I'm a beginner and these are the lenses I'm choosing, I'm going to buy not all of them just a few. What do you recommend? Are these lenses even compatible with the GH2 and I already have a 14-42mm kit lens.

Panasonic LUMIX G 20mm f/1.7 Aspherical Pancake Lens
http://www.amazon.com/...B002IKLJVE
Nikon 50mm f/1.8D AF Nikkor Lens
http://www.amazon.com/...B00005LEN4
Panasonic Lumix G X Vario PZ 14-42mm f/3.5-5.6 Power O. I.S. Lens
http://www.bhphotovideo.com/...Vario.html
Rokinon 7.5mm f/3.5 Ultra Wide-Angle Fisheye Lens
http://www.bhphotovideo.com/...Ultra.html
Panasonic Lumix G Vario 14-45mm f/3.5-5.6
http://www.bhphotovideo.com/...io_14.html

Added (1). Canon EF 50mm f/1.8 II Camera Lens
http://www.amazon.com/...B00007E7JU

What would you use the new lens for? That should dictate what lens you should buy next. You get new lenses to supplement your existing lenses to increase your flexibility as a photographer. You just don't get any lens out there because you can afford it.

http://keerok-photography.blogspot.com/2011/05/lenses-so-many-of-them-there-is-no-best.html

The link above discuss full-frame and 1.5X & 1.6X crop sensor dSLR's only. Convert and compute yourself to get the right focal lengths for your camera.

As far as I know, the GH2 is a micro four-thirds camera. Nikon, Canon and Rokinon will not fit outright without an adapter. You may lose auto functions if you use an adapter though. As much as possible, for complete compatibility with your camera, buy lenses with the same four-thirds mount only.

The 14-45mm is little different from your existing lens, and none of the others (apart from the 20mm, which is of limited use ) will fit.

Spend some time with body and 14-42mm and then work out which extra lenses you need to do what you want. Olympus also make micro four-thirds lenses.