Thermalright Silver Arrow RAM Clearance

Pretty simple. The Thermalright Silver Arrow's RAM Clearance can be seen on the memory I want (Ripjaw X) and over a generic sized, no header, memory.

Here is generic size clearance: http://www.flickr.com/photos/77pat/5399346814

And here is the Ripjaw X clearance: http://i54.tinypic.com/qoakn6.jpg

Different mothboards, but I don't think that affects the height.

The question/concern/(OCD'ish) thing for me is I don't want the fan basically laying on top of the ram, but the logical side of me doubts that the plastic on the fan would affect the RAM in any way and the half centimeter at most that it displaces the fan probably doesn't affect cooling performance either....SO should I go for the Ripjaw X's or the G. Skill ECO (basically the height of generic ram) which I've looked at (and am wondering how compatible it is with P67).

Secondary issues/questions:

I'm assuming the Ripjaw X's "specifically designed for P67 motherboards" will work perfectly fine on the Z68 (basically modified P67 right?)

THERE is also the possibility to completely fix this by just going with the Noctua NH-D14   which has enough clearance for the Ripjaw X's, but I would rather have the Silver Arrow for the lesser amount of noise. They're both basically the same price.

As I'm pretty sure to be going with the Silver Arrow, where should I buy it?   It's not on NewEgg. I guess I could basically go with Amazon.
*I just saw that with the Silver Arrow people buy Corsair Vengeance, how in the world can that RAM fit? (without having only one fan)

*Could someone also tell me if it's a OK idea to get 4 GB now, and whenever, if ever, I need to go up to 8 GB, should I take out my 2 sticks of 2GB and switch to 2 sticks of 4GB, or can I simple add another 2 sticks of 2GB?

THANKS!